If I'm sitting for just a few hours during the day should I still charge the overnight fee or less?

My daycare rates are a bit less than my overnight rates. For comparison, I charge $37 for my overnight care(boarding), but $30 for a whole day of daycare (4-9 hours) or $20 for a half day (<4 hours).

That said, if it's preventing you from taking another overnight client, you might want to charge your full, or nearly full, rate.