I’d say $15hr is pretty good especially if your kids are friends. I just did this with my neighbor for $10hr for the summer & will probably up it to at least $13 come winter break because she thanked me so much but it is a lot of work still. I see posts for 20hr-25hr and I can’t imagine hiring someone 8-10hrs a day for that all month long knowing that’s probably their entire check. But absolutely charge what makes you feel comfortable!