I had a family like this, not exactly the same issues, but still issues that bothered me. I let it go too long and it got to the point where it was really awkward to bring it up. I would just mention it to them now, as opposed to waiting like I did, lol. I do require kids to come prepared for the day (dressed, fed and clean diaper) and would have no problem turning them away and/or getting the parents to change them before leaving.

"Dcd, I see that you are arriving earlier than your scheduled drop offs. Do we need to adjust your contracted times to an earlier drop off (which costs X amount extra)? Alternatively: I have no problem having dcg arrive earlier on occasion but please remember I do require 24 hour notice plus the early drop off fee of $xxx. As well, just a reminder that dcg needs to have breakfast before arrival and be in a clean diaper. If she has not eaten and/or has a soiled diaper, I will have to ask you to take her home for her breakfast and/or change her before leaving her in my care."

I think Dad probably is just not realizing how much stuff like this can throw off the morning in a group setting. (I also think transitioning parents is the worst part of the job.)