I am even stricter. I don't allow for drop off's after 10 am unless for a medical appt and these arrangements are made in advance. I explain to the parents it is not fair to their child to drop them any later then 10 as they won't get any playtime in before lunch and then nap time. All my parents respect this.

I also have no pick ups during nap time, unless for a medical appt which is again, prearranged.