Drop off times

[bright sparks]

You have already done a letter which clearly had little impact so if you are wanting change then you also need to change your approach. Face to face for sure and along with reminding them of the rule also bring up that you have sent a letter home previously but still your rule isn't being adhered too. I would also try to have the kids ready 5 minutes earlier than you need and leave the house early. All of those parents coming at the last minute will have a shock when you aren't there. They are likely to complain as to your whereabouts and say you made them late for work and your obvious comeback after giving them a letter and verbal face to face reminders of this policy is that their lateness makes your children late for school and so you have to prioritize them.