My second ds was an early entrant to K (5 full days) at 4yrs 6mths, moving to 1st at 5yrs 3mths. The early entrance worked really well and he managed to avoid all the problems his older brother had experienced being massively out-of-step with his age peers.
My dd (Nov b'day) will start K next term as an early entrant at 4yrs 5mths, with the view of moving to 1st at the beginning of the next school year. (We're in the Sthn Hemisphere, so school runs Feb - Dec).
I agree with Dottie's list. It is important to make sure the school is really positive about it, too, and understanding of any asynchronies he may have.
Good luck,
Cassandra
