I use this method too rather then posting open and close times. If I post open and close times parents would take advantage of that extra 1/2 hour to do groceries or quick errands. I'd prefer that the parents picked up after work.

I also have a single drive on a busy street. If everyone came at once it would be crazy!

I also want to know when the child should be ready for pick up. I don't want parents surprising me while I'm doing a diaper change or feeding snack. I like to know when to expect someone coming to my home.

Also, if you post open hours at 7am, but for one specific day your 7am isn't coming and your next one doesn't arrive until 8, I want to sleep in and not worry about someone surprising me at 7am.