Hi W.
I am in home child care too, and I think if she drops the baby off for 4hrs or more I would charge her the daily rate. I would take what you said you would charge her weekly and divide it by 5 and make that her daily rate. I always felt after 4 or 5 hrs it should be considered a full day. It would probably cost a parent more to pay me by the hour v. the daily rate after 5hrs. If she drops the baby off for an hour or 2 I would charge her the going hourly rate in your area for the age of the baby. I think here in OKC it is about $7 an hour. If you have all ready watched the baby for a few hours and not charged her I would consider it good business but put an end to it nicely. I would tell the mom you have enjoyed getting to know the baby and would love to continue to have her as a drop in until she goes back to work full time, but if the baby comes less then 4hrs you will charge her (what ever you charge an hour) and if she comes more then 4hrs you will charge her the daily rate and explain how you got to that rate.
You will not look greedy at all. This is what you do for a living. I don't know why parents think we should do it for free or less. I watched a friends child once for about 6 weeks over the summer for about an hour or hour and half a day, and I said they did not have to pay me. I asked that they send her w/ a snack and that's it. The little girl is friends w/ my son so they played well together and I watched the little girl for several years and they paid me very well. So as friends and as a good fair business I did it for free. I forget why, but for 2 weeks they needed someone to watch her all day all week and instead of asking me to do it they paid another lady to watch her. And then came back to me for their free care. I think they (for a short time, we are still friends) lost respect for me or just took advantage of me. I don't give my services away unless it is one hour or so to get to know the child, that is good business, and I make it clear this one time there is no charge, but in the future get to know visits are welcome and encouraged but I charge $7 and hour. Just remember you are a business like any other. Know other business gives away stuff.
Well good luck, I hope it all works out well. Keep us posted on how it all works out.
T.