I charge a $200/month holding fee. IMO, you want to make it substantial enough that they will think twice about loosing all that money they invested in your d/c if by chance they pull out. Some people charge half fees some people will make them pay full pop. I have been burnt a couple of times by only charging a 1 time fee and also to little of a holding fee...so I decided to do it monthly and up the fee. It also shows they are serious about enrolling with your daycare.