What's the earliest you can complete the community center?

stardew-valley

On Spring 5 Year 1, Lewis will show the player the community center. The day after, you will be able to start making progress towards completing the bundles within. Each bundle requires specific items (sometimes of a specific quality) to complete, and many of these items are only available during certain seasons, which means that progress is "locked" by how long you've been playing.

Based on that info, what is the earliest you can complete the community center?

Solution 1:

Assuming you get all the items via the normal methods (i.e. farming, raising animals, fishing, etc.), the earliest you can complete all the bundles in the community center is Summer 10 Year 2 (or Summer 6 Year 2 if you have Agriculturist + Deluxe Speed Gro). This date is the earliest you can grow a Red Cabbage, which is the latest required item for a bundle.

However, there are several ways to speed up this timeline:

The Traveling Cart, which sells a random assortment of foods and seeds throughout the year. It is possible to buy a lot of otherwise time-gated requirements) from the lady in the cart. She appears on Fridays and Sundays in a clearing west of Marnie's ranch (close to the entrance to the Secret Woods). Keep in mind that she charges a pretty big markup on items.
Once you earn 25,000 total gold, Demetrius will stop by and offer to set up your cave as a research area. He will let you decide whether to study fruit bats (who will leave random fruit on the floor) or mushrooms (which grow random mushrooms). Personally I think the fruit bats are more useful for completing the bundles, but both options are helpful.
The Stardrop Saloon has a chance of selling Maki Rolls, which are needed for the Chef's Bundle on the Bulletin Board.
Once you unlock the Greenhouse (earliest Fall Year 1), you can start growing any crops you might have missed in earlier seasons, if you have leftover seeds. This might save a season or two of waiting.

If you get really lucky, you could theoretically complete the community center in Winter of Year 1 (or maybe even Fall, if you're insanely lucky).

Here's the earliest you can complete each bundle without using any of the above tips:

Crafts Room - Winter Year 1

Spring Foraging Bundle - All items can be found by foraging in Spring Year 1.

Summer Foraging Bundle. - All items can be found by foraging in Summer Year 1.

Fall Foraging Bundle - All items can be found by foraging in Fall Year 1.

Winter Foraging Bundle - All items can be found by foraging in Winter Year 1.

Construction Bundle - Depends on how quickly you upgrade your axe so you can chop the large stumps to get hardwood. Can usually be achieved by late Spring Year 1.

Exotic Foraging Bundle - This bundle requires 5 out of 9 options. Maple Syrup, Oak Resin, and Pine Tar are really easy to get as they only require a tapper. Cave carrots are also super common in the mines. For the last item, you can either look for a red/purple mushroom in the mines, or upgrade your axe twice and hope to find a morel mushroom in the Secret Woods before the end of the first Spring. Either way, this can be completed Spring Year 1.

Pantry - Fall Year 1

Spring Crops Bundle - All items can be grown in Spring Year 1.

Summer Crops Bundle - All items can be grown in Summer Year 1.

Fall Crops Bundle - All items can be grown in Fall Year 1.

Quality Crops Bundle - Requires 3 of 4 options. Since melons and corn are both available in Summer, this bundle can be completed Summer Year 1, though you have more chances to complete in Fall if you don't grow enough gold quality crops.

Animal Bundle - Depends entirely on when you have enough money to start animal farming. Theoretically you can complete it in Spring Year 1, though Summer or Fall is probably more realistic.

Artisan Bundle - Requires 6 out of 12 options. Most of the available options are fruit, which can be acquired with fruit trees. Cloth is easy to get (recycle newspaper) and honey/jam is also relatively simple, so this can be completed by Summer Year 1 if you manage your money well.

Fish Tank - Fall Year 1

River Fish Bundle - You're limited by the Tiger Trout, which only starts appearing in Fall Year 1.

Lake Fish Bundle - Sturgeon are the limiting fish in this bundle, so you cannot complete it until Summer Year 1.

Ocean Fish Bundle - The fish you need don't start appearing until Summer Year 1.

Night Fishing Bundle - Walleye don't show up until Fall Year 1.

Crab Pot Bundle - You need 5 out of 10 options. All options can be caught in any season, and I believe some can be foraged on the beach as well. Theoretically you can finish this in Spring Year 1, though most probably finish in Summer.

Specialty Fish Bundle - There's two limiting factors here - Pufferfish can only be found in Summer, so that's the earliest you can complete the bundle. Sandfish can only be caught in Calico Desert, which is inaccessible until you finish the Vault (costs 42,500 gp in total). Though you can theoretically finish this bundle in Summer Year 1, many people don't have enough money to complete the Vault until at least Fall.

Boiler Room - Spring/Summer Year 1

Blacksmith's Bundle - Requires gold ore, which you can either buy directly from Clint or find in the mines at level 80+. Theoretically completeable in Spring Year 1.

Geologist's Bundle - Fire Quartz can only be found in the mines at layers 80-120, so it takes a while to work your way down there. Theoretically you can complete this in Spring 1, though Summer is more likely.

Adventurer's Bundle - Void Essence is dropped by Shadow Brutes on floors 80+, so again, you can theoretically complete this in Spring Year 1 but Summer is more likely.

Bulletin Board - Summer Year 2

Chef's Bundle - You learn how to make Maki Rolls on Summer 21 Year 1, so that's the absolute earliest you can complete this bundle. However since it requires truffles (which requires a Deluxe Barn for pigs, plus the cost of the pig itself), many people don't manage to complete this until Fall Year 1 or Spring Year 2.

Dye Bundle - The red cabbage is the main limiting factor here, as it is only available Summer Year 2.

Field Research Bundle - The Nautilus shell can only be found by foraging on the beach in Winter, so Winter Year 1 is the earliest this bundle can be completed.

Fodder Bundle - Apples are the hardest part of this bundle to come by, but as long as you've grown an apple tree, you can complete this in Fall Year 1.

Enchanter's Bundle - Pomegranates are only available in the Fall, so that's when this bundle can be completed (Year 1).

Vault - Varies

All Bundles - These bundles are cash only, so the only limiting factor is how much money you have. Theoretically you could complete these by Spring Year 1, but that's pretty unrealistic. I think most people finish this by late Summer/early Fall, or possibly even Winter Year 1.

Solution 2:

TL;DR

Buy Red Cabbage (RC), crocus, snow yam, fall crops, fall fish from traveling cart (TC). Get lucky with fruit. Have crop fairy speed up summer crops - Summer Y1 D2
Buy RC, crocus, snow yam, fall crops, fall fish, from TC. Get lucky with fruit - Summer Y1 D9
Buy RC, crocus, and snow yam from TC. Get lucky with fall crops - Fall Y1 D3

(Realistic completions)

Buy RC, crocus, and snow yam from TC - Fall Y1 D10
Buy RC from TC - Fall Y1 D16
No TC - Summer Y2 D6

Explanation:

It's helpful to see which community center items you usually get late into the game.

Note that money is assumed not to be a problem. It's possible to rush fishing and get into skull cavern by as early as the 2nd week of spring. ~10 optimal runs of skull cavern should be more than enough to pay for everything required for the community center. Alternatively in multiplayer, you have more people working together and can split up the tasks, getting into skull cavern in spring while still maintaining a relatively sane playthrough.

Red Cabbage (or RC for short) - Summer Y2
Winter Foragables (Crocus, Snow Yam, Winter Root, Crystal Fruit) - Winter Y1
Nautilus Shell - Winter Y1
Fall Crops - Fall Y1 D10 (The earliest for pumpkins with max boosts)
Apples Fodder Bundle - Fall Y1 D3
Walleye - Fall Y1 D2 (Walleye requires fall and rain, but it can't rain on the 1st of a season)
Gold Quality Melons - Summer Y1 D9 (Can't be purchased from the traveling merchant)

For items only obtainable in Winter Y1 and after, there are workarounds. Apart from red cabbage which you can only get from the traveling cart (you can upload your save to stardew predictor to check), the winter foragables have alternative gathering methods.

The Nautilus Shell may be received as a gift from Demetrius. If he sends you something in the mail, but it's not the Nautilus Shell, you can keep restarting the day to refresh the gift.
Winter Root and Crystal Fruit can be found on floors 41-79 in the mines. If you put them in a seedmaker, you can get winter seeds, which can be planted in the greenhouse.
If you utilize deluxe speed gro and agriculturalist, you'll finish up the last items on Fall Y1 D16, which inconveniently is the day of the stardew valley fair. However, you can rush back to the community center in the night after the fair is over and finish the last bundle.

Here's a rundown of the resulting times.

No travelling cart (or TC for short) (Summer Y2 D6 due to RC)
Buy RC (Fall Y1 D16 due to crocus and snow yam)
Buy RC, snow yam, and crocus (Fall Y1 D10 due to pumpkin)

With some luck, it's theoretically possible to finish the community center even faster.

Crop Fairy or TC for pumpkin, eggplant, and yam. Buy RC, snow yam, and crocus (Fall Y1 D3 due to apples)
Fruit Bat Cave and/or TC yielding 3 apples and 1 pomegranate. Buy RC, snow yam, crocus, yam, eggplant, pumpkin, walleye, and tiger trout (Summer Y1 D9 due to gold quality melons)
Crop Fairy on Summer Y1 D2, Fruit Bat Cave and/or TC yielding 3 apples and 1 pomegranate. Buy RC, snow yam, crocus, yam, eggplant, pumpkin, corn, walleye, tiger trout. The crop fairy needs to hit the center of a 5x5 space, consisting of 10 wheat, 6 melons, 5 corn, 1 poppy, 1 hot pepper, 1 blueberry, 1 tomato. Wheat must be the same quality, 5 melons must be gold quality, 5 corn must be gold quality. (Summer Y1 D2 due to gold quality melons and corn, may only be possible in multiplayer)

Fall Y1 D10 is the fastest realistic time of finishing the community center, but Summer Y1 D2 is the fastest possible time of finishing the community center.