I don't understand why you WOULDN'T put him on the bus with all the other kids. I can't believe the school will have hallways full of parents - what a nightmare and what an impediment to learning, calm and safety! He knows the building, he will already know the teacher, and he will know where to go. I'm sure they will have staff available.
My parents never ever took me to school, and I never took my son. Riding the bus is a way to feel like a big kid and to feel like the other kids. What is going to be different on the 2nd or 5th or 80th day of school? He's got to ride the bus sometime. Usually schools have experienced drivers for the little kids, or bus monitors, or staff to meet the bus and patrol the halls. I think it would be much nicer if all those parents were not there!
I've taught in several schools and have never seen hallways full of parents - if you have concerns about that, you need to talk to the school about making it a more orderly and calm environment.