Especially if they are in school/ daycare part or full time?

Currently my 3.5 year old goes to preschool two mornings a week, and she has a gymnastics class on other morning. I think she would really enjoy another scheduled activity-I think dance- but I'm already having trouble finding one that works with our schedule- which I think is more flexible than most! A lot of things are early afternoon, when she sometimes naps but little sister needs to be napping. Next year she goes to four mornings a week preschool so we will be more limited.

So I'm curious when other kids are doing their extra classes and activities. If they are in full time daycare, do they offer it there, if you stay home, do you just mess with other siblings naps? Or mostly just weekends?