Hi J.. I'm a mom in Roseville with a 20 month old with Downs. What a wonderful journey you are embarking on. I want a bumper sticker that says, "My child has more chromosomes than your child!" LOL Our little guy is the light of our lives and suprises us each day with what he does.
You can call the Warmline at (800) 660-7995. They are a non-profit that is ran by parents of special needs kids. They can give you all the info about support groups, services, etc.
Once your son gets his Regional Center services in place, make sure your case manager refers him to their Downs clinic. Dr. Wardinsky runs it and he's wonderful to explain so much about Downs and what to expect.
If you want to talk more, let me know.
L.