Ratio wise you are fine because on any given day you have no more than 5 daycare children - your own children do not count in those numbers so the 7 of 5 daycare plus 2 own is fine. Because of the days you have the 5 already remember that you can't take any other children that would need those days because you can not go over the 5 daycare on any day even for an hour or two. By the way you can have any age mix you want with only the 5 children limit when you are not with an agency so take more under 2 if you think you can handle them.

To guage the workload make a list of those in school and those at home and how many you will have what days. You might find that while a couple days will be really busy with 7 there will be days you only have a few at home to care for while they others are at school. If you do the school/bus runs be sure you have a method in place to deal with the little ones needing naps or not walking depending on the distance.