Mickyc.....I totally understand where your coming from. I think if your up front and honest with the parents in the beginning then it should be no problem. After all we are only allowed to have 5 kids at one time and we do love our jobs but need to make a living as well.
When it comes to the parents many times they do not consider how we feel for instance when I just purchased my new home a month ago I gave all my dc families a months notice. Within that same week all found new daycares and left early even after I told them I would be available until October 25. The bottom line is you need to look out for yourself and your family.