210 is early and inconvenient for sure. Mine nap from 1230-3/330 even the one who has a 45 min nap in the morning. Most days I am waking 3 out of the 4 up. They all nap in same room but I do from time to time have had to put one just outside the nap room. ( usually due to an early riser)

I would wake them 15-20 mins prior to when you need to leave. I would have their sippy cups ready to go and they can have a drink in the stroller. I would make sure they are still getting at least 2.5 hours to nap and give yourself 30 mins for lunch.

If you are finding it doesn't work maybe you could hire someone to walk him home?