I make it very clear that I value my family time and am not available to do even 1 min of over time.
If potential daycare parents have any doubt whatsoever about being able to make it here on time I explain to them that this is not the right place for them.

I have never had anyone show up late.
In the even it were to happen , my fees are $10 for the first 15 minutes , then $1 /min after that.