I've been going through this now. DS (turning 5 in Aug) will be starting in an Independent study program in a neighboring district in K and be moved to 1st at the semester. He's currently doing 2nd grade reading and late second early/third grade math. His teacher will start him close to his level and then let him go as fast as he wants until he gets to stuff he doesn't know yet whatever that level may be.
The k then 1 stuff is because in CA you cannot start K before 5 at December of that year. However once they are in K they can be moved the same day to 1st if that's what the teacher thinks is right. Ridiculous... Anyway we're getting what we think he needs so it's working out.
It has been a long road though... It took me almost a month just to find someone in our district who even understood the concept of early entrance K. That person was the head of the GATE program and to this day she is really the only person in that district that "gets" it.
In some states Gifted Education falls under Special Education. If you are in one of those states you might have a bit more support from the schools than we have here.
My best suggestion is to find and talk to whoever is in charge of Gifted Education in your district. Keep it simple, be direct and don't apologize for your child. Do tell them about your concerns contacting the schools. The person you are talking to knows about gifted kids (hopefully) and should be at least somewhat sympathetic and understanding of your situation.
If you can get early entrance, meet the teacher you child will have BEFORE the year starts and make sure it is a good fit. I had a homeschool charter teacher lecture me for nearly half an hour against a grade skip in front of my son... Obviously we didn't end up there.
