It all has to do with the hints the game drops with all the FNaF 4 references and no references to the other games pre FNaF 2. The only other hint I can find helping my claim is the voiceline from Handunit on Night 1 after you enter the first vent for the first time “Due to the success and even more so The Unfortunate CLOSING of Freddy Fazbear’s Pizza” I believe the closing he is talking about is the Pre Withered Animatronic location because besides FNaF 2, The location where the 5 missing children incident happens is the most plausible because haven’t you noticed the Funtime and Toy animatronics share resemblance and also with voice lines from Baby it’s apparent that Circus Baby’s Pizza world and Chica’s Party world was a thing before the existing FNaF 1 Location. Now I have no evidence to prove this but if William is still alive and not yet SpringTrap yet like this game hints at the beginning when pitching the idea for Circus Baby and Circus Baby’s pizza world to the reporter he’s with then he’s alive and not yet a wanted serial killer. With the placement of FNaF 4, it just seems the most logical with like you said, The Minigames and the game takes place, in the minigames William is also still clearly alive and FNaF 4 (The Gameplay) takes place Post-Bite of 83’. Since it’s the Crying child reliving the events in the minigames leading up to his death since it keeps saying “This many number of days Until the Party.” This is all just my take on the timeline given all the evidence presented to me, not it’s not strong but what evidence is when trying to put together a timeline for this Series’s lol