While I don't have experience with the Regional Center, we had similar meetings after our daughter was diagnosed. Autism Speaks has a useful 100 day kit (https://www.autismspeaks.org/family-services/to...).

Looking at http://sdrc.org/?page_id=20, it sounds like they will review your son's diagnosis and work to align you with resources. The question you asked on this site "what can [the Regional Center] do for [my kid]?" is perfectly appropriate to ask during your appointment.

If your experience is similar to ours, you'll be presented with many services and you'll have to decide, sometimes through trial and error, which ones are right for your son.

No one knows your son better than you, trust your instincts. After all, if it wasn't for what you've done for your son so far, you wouldn't have a diagnosis. Stay in charge and continue being his #1 advocate.