Just my own opinion - but personally, I wouldn't worry about early entrance to kindergarten. Enjoy that year at home having fun together and if he learns, so be it. I wouldn't homeschool kindergarten either.
Instead, make sure he gets lots of social interaction and physical exercise. Keep him well rounded (to the extent that you can).
Read and learn now. And pat yourself on the back. So many of us had kids like that at that age and didn't even begin to recognize that something not quite normal was going on. Just today I had lunch with someone who asked when we knew with my son.... so embarassing to answer that question.
Mary
