ok so if I am reading this right this is what is going on:

Family 1 - Leaving sometime in May. So spot open as of June 2
Family 2 - Leaving so spot open on XX date
Family 3 - wants full time by the end of March
Family 4 - Might be leaving by xx date in April. Leaving a spot open
Family 5 - one full time kid. possible pt kid for summer

-Start looking for a replace for family #1 to start as of June 2
- Start looking to fill family #2's spot. for the week after they leave (or around that time)
- Family #3 will go full time
-Family #4 - start looking for a replacement to start as of May 5
- family #5 - have one full time kid in care and wants to send they School aged kid 2 days over the summer. if you need to take on the pt kid to help full a spot (pay bills) until you find another full time kid do so.

looks like you will have at least 2 to 3 spots opening up very soon. So start looking