Which rooms? I did it but nothing is showing, I put it on room 109, 112, 113
Is absolutely random but if it works for you, if you save game right before she jumpscares you (no need to predict just save at at the start of every day) you can load your saved game and she is gonna jumpscare you again at the same exact time either in the cameras or desk. This allows you to try again even if you fail as the game already chooses at which hour she is gonna spawn at 00:00 hours every day. And yeah she may simply not spawn in a whole day.