Big Bank Job - 12 Angry Minutes

In the Big Bank Job, there is an achievement for accomplishing the entire job in 12 minutes.

What pre-planning options and actions within the bank are essential to finish this job as per the requirements of the achievement?

Assume I'm using a group of 4 players, no AI, and we're playing on normal difficulty as I would expect it would be easier to do on this mode.

Solution 1:

Loud, fast, coordinated, and on Hard

I am going to make the following assumptions for this:

You have 4 players that are familiar with the heist and what Plan B (loud) entails
That at least two players can consistently get the correct computer for the time-lock on the first try whenever luck isn't severely in your favor. Look up the "It Takes Two To Tango" achievement for specifics on how to do this.
That you want to do it on the easiest difficulty possible (Which is hard - Normal difficulty is ineligible for the achievement)
And you want the least amount of headaches (which rules out the fast-and-stealthy approach)

The Preplanning

The plan you have walking in can make all the difference, and proper asset selection makes it a lot easier to do.

Escape Plan: You will want the Bus escape (6 favors). It's a safe, fast extraction and if the vault door is in the ideal spot (2F, on the left), that's even less ground that has to be covered.
Hacking: The Time Lock (2 Favors) is essential as it shaves off 30 seconds on the time-lock. That's a 30-second cushion you get for stuff like the HUGE_LANCE (aka The Beast) breaking.
Other assets: Some people prefer having the zip-line, others prefer making sure a keycard is available because they don't want to bring ECMs. Your discretion here.

The Loadout

You will want the following:

A Saw. Shaped charges can suffice as a backup, but the saw is faster. Seconds will likely matter.
2 ECMs, with ECM Overdrive Aced. This is for the two Security Doors that will have to be opened (the Server door and the roof door, more on that later)
Appropriate Armor. For Ghost builds, a Light Ballistic Vest will probably fare much better than a CTV due to the high dodge. Enforcers may want to take Flak Jacket (or possibly heavier). Note that the ICTV is overkill, especially on Hard.

The Execution

Stealth is a non-issue here, and maintaining stealth can cause time to be wasted later. The person with ECMs will first locate the server room and open it, hitting the computer (just in case it works - it's rare, but it happens). Then, two people (hopefully NOT including the person with ECMs) will work on the computers while the ECM guy hits the roof and opens the other door to handle the time lock rewiring. Fourth guy will be on the roof, immediately heading to the crane once stealth breaks (the Zip-Line cannot be set beforehand) to start moving Floyd the giant pig into position.

For the two people on computers, once the person at the workstations confirms the correct computer, the server person will move to the time-lock switch to hit it at the earliest moment. Once it is hit, the ECM guy (or whoever's on the roof) will need to rewire the time-lock code, and then the switch will need to be hit a second time. If all goes to plan, Floyd should drop with at least 30 seconds still left on the time lock (60 if you did not buy the corresponding favor), at which point everyone should get a spare part and move the bags to the time lock door. You should, ideally, be through the door around the 4:30 mark (Time Lock takes 3 minutes before favor, factor in about a minute and a half to get it going in the first place).

After that, it is just speedrunning the remainder of the heist and making sure to grab CASH BAGS, not gold bags. You will need 4 bags, or one per player.