I would message her back and say
"I think it would be great if you could drop him off x:xx on ?date?. I think it would be great to start off with you leaving him about 2-3 hours and I will just charge $15 (or whatever the fee is that you want to charge). This is going to be a great opportunity for him to get used to the house, the other children and myself and I think it will really make the transition into the daycare easier. I also think it would be a great idea if we can set up a second day and extend it a few hours longer so he gets another time here with the daycare before he is left a full day. It just makes it more comfortable for everyone to ease into the situation and address any issues that might happen before you need to leave him a whole day. I hope this works for you and please message me back a day or time when you want to do the first drop off for play time. Hopefully it will be a nice chance for you to get some errands done and give you some reassurance as well."


That's probably something along the lines I would say to convey the message she is not exactly invited. lol