For anyone having trouble and wanting to beat 4/20 mode before they change the Ai of Freddy (spoilers obviously):
The night is about 8 min and 40 sec, Freddy moves every 77 sec and will end the run with the 6th movement. Therefore you need to stall her for atleast 59 sec during the course of the night. I basicly pulled the cam up every 75 seconds after she moved until I heard someone at the door. (And the cam does not have to be on her)
For Foxy I just shortly flipped the camera up and down basicly every second. With this strategy power went off at 8min 30sec and the rest I just waited in the dark. (And yes for the exact timings I had a timer running on my phone ^^)