One triggers at the pool when you "get some sun", there's a 30% chance it will trigger. The chance re-rolls every day as opposed to every time you try to trigger the scene, so if you don't get it once then it won't trigger that day.And I started a new game to see the newly added old house events, but I don't know what the new events are. Hahaha
The scene that can trigger when you take a shower has a 30% chance of triggering. These two are only accessible before you cook for Sarah.
The scene with Sarah that can trigger on weekdays can only trigger after you've started the thesis, it has two variations that are randomly chosen.