I am fortunate that my husband works nearby and will come and watch the kids should I have a medical app. I try to schedule my appointments after drop off or at afternoon nap. I will have a snack ready for him to serve should he need it. If you don't have anyone to do this, then I would schedule your app for the earliest in the day possible or the latest possible and tell the parents they must adjust their drop off/pick up times to accomodate you.