Some help with fnaf 2

So I’m trying to beat Fnaf 2 and I wanna ask something, does puting the mask in during a black out sequence aldo deter animatronics in the vents or do i need to keep it on for aditional time? Sometime I get, let’s day mangle, making it’s noise while I’m on the music box but I take off, there’s a black out sequence, then mangle just vanishes, other times, that eric cartman looking ahh balloon boy is stuck chilling in vents after i check the lights and he doesnt leave like mangle does? Also, I’m still struggling to find what the “safety window” is after flashing foxy. Sometimes, I can flash him then wait the whole night without having to do so again, other times, i flash him, then get jumpscared by him less than a pico second before i change to cams. Can someone help me out please?