Yes, make them pay for 4 days/week, and they must be set days. No moving the days around as they like, as that could equate to a full time spot. Keep interviewing anyway, as they may choose to leave. Make the new family pick set days(if not full time) and ask for payment 2 weeks in advance. I bill parents on the 1st and 15th of every month, and get 6 months of post dated cheques up front.