Seems harsh to me.

Maybe re word so it's a little more friendlier. " due to late drop offs... " " in order to maintain consistency in my program for the benefit of all children... "

Just a thought. I know if I was going to a daycare that came out with this memo I would be moving on. It's not the hours that would make me move on, it would be the tone in which it was written. It almost feels like someones done something wrong so you're coming down on everyone.