I have one and she pays me at the beginning of the month for a total of 12 days (min payment required). Her and I both keep track of the days dck is here and if it's over 12 she pays for the extra days. At first she was paying me for just the days dck was here but some months it was only 9 days, and I told her in fairness to my other part timer, I need a min. of 3 days per week, or 12 per month. She agreed and so far it's worked out really well.