Well, first, I would never put a child in the tub, so you are going way above the call of duty. If the child is that uncomfortable and needs medication for their rash then I would send them home.

Then, if a family was showing up a 1/2 hour before they were scheduled I would have a sit down meeting with them and ask them if these are the new hours and let them know that they can't just show up whenever it is convenient for them. What if you went 1/2 hour early to your dentist or doctor? Would they just say, oh sure, if it's more convenient for you we'll get you right in. NO!

It's all about RESPECT FOR YOUR DAYCARE PROVIDER!!!