Things you can try: See if they have a "find your class room day." Most schools have a day right before school starts where you can go to school and find their classroom, cubbie and desk.
If they don't have that, call and ask if you can have a tour.
Try and see if you can get his bus route. What streets he is going on to pick up other kids. Drive him on it a couple of times and point out things he can recognize. Maybe you can even draw him a map with pictures of places the way. If he is walking to school you can do the same.... there is that red hydrant.....etc. He can take the map with him.
Let him identify with other kids. "Johnny is going too. He will be in kindergarten just like you." Find that familiar face.
Try and talk with his teacher beforehand. Most teachers will respect your involvement and help him out even more. Ask if you can have the class schedule and make a picture diagram of the things they will be doing in order so he knows what to expect during the day.
Go to the school and play on the playground everyday up until he starts. It will feel a little familiar to him even though it's just the outside.
Make sure you pack his FAVORITE things for his lunch.
Have something he can keep in his pocket as a form of comfort. Something that is small and not disturbing that he can hold on to if he gets upset.
Hope these help. It did for our babe.