A two week, non-refundable deposit that becomes their first two weeks of care. Either one of us can term without notice during these two weeks.

Then for payment, I ask for payment on drop-off on the first day of care for the week. No pay, no stay. If they don't pay for that first day (say on the Monday) at drop-off, I refuse care. Then an additional $20/day for late fee fines. Never had to use it, but it makes sure that they pay on time!