Wait Time for NPCs to Move In

I have recently returned to play Terraria and try Journey's End Master Mode. Got lucky and defeated a Pinky as soon as I begin my game, which gives me a few gold coins, and somehow managed to find a Heart Crystal and some Bombs inside the first natural cave that I entered. Then I build a few houses (confirmed as valid housing) in preparation for NPCs to move in. It all happened on the first day, it was a great start, I thought. But then...

Currently on the 5th night. Neither Merchant, Nurse, nor Demolitionist have moved into these houses that I prepared. The same with Arms Dealer and Dye Trader, these randomly spawning NPCs just won't move in even with their prerequisites filled.

Is there any new rules for NPC spawning in Master Mode? Or have I angered RNGsus for accidentally butchering those bunnies and squirrels while cutting down trees?

There have been no changes to NPC spawning behaviour in Master Mode. Double check that the houses you've built are valid and that you've met the requirements, as nothing else could be preventing NPCs from moving in.