I think that it is very hard to ascertain how gifted a child is at age two or what his future academic needs may be. He sounds like some kind of gifted but whether that will prove later to be the type or level of giftedness that can be accommodated in a public school classroom with gifted enrichment or will need grade acceleration or some sort of alternative arrangement isn't easy to say at this point.
FWIW, age cut-offs for school can change. My youngest just turned 11 last week. When she was your ds' age, she too would have missed the K cut-off where we live. The year she started K, one of the local districts pushed their cut-off out to a later date (10/1 rather than 9/15) which allowed her to get in by mere days. She changed districts later to one that had retained the 9/15 cut-off, but districts tend to honor other districts' student placement and did not make her repeat K. Since then, the governor of our state has signed a bill allowing for early admission to K for "highly advanced" gifted children, so kids who miss even the 10/1 date, which is the latest the state funds, can get in if they test highly enough.
