Probably you either need to enter the room of your sister at 21 on sunday to watch Bill interact with your sister there, or you need to enter your sisters room at 10 am to see what he has given to her.
Edit note: If you just changed a variable to get to that point, maybe that broke the quest chain. Oh and after taking the money from Bill, you will need to watch the scene at 12 on Sunday three times for it to get back to the point you were before you interrupted last time. So it will at least take 3 weeks to progress. This game has never messed around when it comes to grind. I rolled my eyes back when I realized I needed 70+ in erotic massage.