I follow the school calendar too. I start work the week before school if the teachers need it to prepare their rooms and attend inservice meetings. I offer this week at a drop in rate if they choose not to attend this week or attend just a few days.
I charge for school holidays and breaks that I'm closed except for Christmas break. I'm off without pay and consider it their christmas gift.
I charge the same weekly rate for snow days too. I do give them the option of bringing their kids if they really want to, but I'd prefer to just be closed.
I do not charge for the summer and I do not watch any kids during the summer. I will do a very rare drop in at my drop in rate, but typically I'm not home during the summer - I'm busy with my own kids activities.
I also offer the last week of school at the drop in rate if they choose to come. - I do this because sometimes the last day of school falls on a monday and if I charge the weekly rate, some parents feel they need to bring their kids the whole week. I'd rather have a few less kids and possibly start my summer a little sooner. But I am officially open if they choose to come the whole week and pay for it.
I also charge one week's rate to hold their spot through the summer which is then applied to the last week of care for the following school year. Only because it deters the families that just want to ensure a spot somewhere but don't actually plan on attending or paying anything. Then I have less drop in enrollment from year to year. If they've already paid something then they tend to return.