My experience is that the school never wanted to talk with me until at least a few weeks in. You can certainly try to go to the school 504 specialist, but at least in my school district they are on on vacation until August or about 2 weeks before school begins. And then the psychologists/counselors are very busy.
The other advantage to waiting a few weeks is you may have a better handle on what changes are in fact needed. And the new teachers can come to the meeting, and they may know better what accommodations would be most helpful.
Good Luck.
