I put a drop-off cut-off time in my policies, I set it to coincide with morning snack time.
It fixed it.
I don't just lock the door and ignore because this always ended up with them ringing the bell, knocking and disrupting us, anyway. When I see/hear them pull up (driveway alarm/camera) I walk out and tell them I am not accepting late arrivals. Face to face, before they can get their child out of the car seat works fastest. I then walk back in, it takes 30-45 seconds depending on the weather.
I do have the exclusion for well-child checks, with notice, at least the day prior. They bring their updated immunization form or health report as proof. Win/Win.
