I think one of the biggest things is understanding *why* they do it. It’s literally because the part of the brain that says “you only got 10 minutes left” is kinda broken. One tip I’ve found helpful is clocks. My bedroom clock for some reason won’t work (not getting connection from the battery) and I was like 10 minutes late the first day. The next day I was more conscious about it and made sure to check the time on my phone before work and was on time.
I have a friend who is about 70 and struggles, so it’s understanding that our brains our broken. That may help take away some of the anxiety. The child may feel like they aren’t doing good enough but not realize they just have to think a little harder to be more cognizant of it. That may or may not work depending on the age and understanding of the kid.