My 4yo has a meltdown every morning before school

Wake-up to uniform to car to classroom in 15 minutes = complete dysregulation. Not because they don't like school—because transitions shred their nervous system.

By the time we reach school, they're crying, I'm frustrated, teacher thinks it's a behavior problem. Nobody understands it's a regulation issue.

What morning routine/transition hack actually works? How do you advocate for understanding at school?