A few questions re: potential DCK's

I have a short term arrangement with a friend of the family, from end of Jan/ start of Feb 2013 until Summer 2013. When that little girl's grandmother retires, she will be her caregiver. I have another parent who would like for me to care for her daughter once the first girl's spot frees up. I have explained to the second mom that i cannot promise anything at all. First of all, i have already committed to the first family, and i do not know for certain when (or if) the child will be leaving my care, therefore i can't give her a firm start date. I am flattered that she keeps asking me so she can plan her care, but I can't give her any certainties at this time. Besides, it's way too early, i will only interview 1-2 months before her daughter starts care and there is never a guarantee that i will accept the child. I also mentioned to her that there is always the possibility of the first child remaining in my care for longer than the proposed arrangement, or of her not even leaving my care, and she gets it. I think i have covered all my bases, in your opinions, Am I handling it right? Anything else i should add/leave out?

I also want your opinions on how to handle finances and how to charge. Both sets of parents have varying schedules, but i will always have a copy of their schedules, so i know well in advance what days i have the kids, aside from a 'drop in' day. In both families' instances, some weeks i may have the respective children several days a week, or only a few days, or none at all. In both families instances, it will be early drop offs, like a 6 am start, to which they are all aware that since i open at 7.30 am, they will be paying a premium on top of my regular rate, and they are ok with it. I have suggested to both moms that i look at a few months worth of schedules to get an idea of how many days per month i will care for the kids and take it from there. They all understand that they will be paying whether the child comes or not, so i need to try to figure out how to charge. I am a little lost on this one so any help is appreciated!!!

Well since they are essentially taking a full time spot cause the chances of finding someone to fill the empty days are slim to none so I would charge my full time rate and then tack on an extra fee for the days they will be dropping off early

I would do the same as Crayola...I won't keep a space available without payment. So full-time fees would be due and then they can use however many days they want. I have a child who comes four days per week now and they pay for five because it would be impossible and undesirable for me to fill a one day a week spot.