The prepay like lilbiddapopcorn said works well unless you decide to charge by the hour. If you do this then you will also need to have a cut off date also. Monday is always a good day if Friday is usually pay day. If you charge by the hour then you take the chance of loosing aweeks pay. This is the way I have done it for the last 2 yrs & have not had a problem with my parents not paying on time. I did have a problem with a state aide family that did not want to pay the fees they accumulated & never got paid for the fees. It is a good idea to have a contract & a policy written up with all your rules. I used
http://www.thedaycarelady.com/form.htm to get a start on mine then just changed them a bit to meet my needs.