Is there anyone with an ASD child that attends two schools?

I'm interested in hearing stories of how to help them transition and understand without freaking out too much.

We can't send him to just one school because it would mean travelling over an hour on a bus with high school students (DS1 is almost 5). So next year he will do 3 days a week at the local school and then travel 2 days a week, with the school, to the bigger school.

Any tips would be fabulous.