Usually, students report directly to their classrooms on the first day of school. (And usually the class lists are posted near the school office). But some schools kick off the school year with a quick assembly of the whole school.
The best thing to do is call the school and find out what you need to know to help your son have a great first day. They may have a packet of information about school supplies, dress code/uniform, the lunch program and other information that will help get you off to a smooth start. If you didn't get that in the mail, you may be able to get the information over the phone or pick up the packet in the school office.
I see you live in FL. I know that my sons school does an open house a day or two before school starts. I would suggest calling your sons school and ask about an open house or if you can meet your child's teacher.
Hope this helps!!! Good luck