I am a fan of early entry - it has worked quite well for our oldest so far. We may be looking at further acceleration, but it did give DS two good years in brick and mortar school. I agree that the playful nature of those introductory months can work quite well for gifted kids provided they are clearly younger than the rest of their classmates. After two years, things appear tie be coming. Apart at the seams a bit - pace gets more of an issue after a while.
I would research the early entrance requirements for your state very carefully and then book a testing date as late as possible (if possible, with the option to squeeze in another one in time in case he's sick). From my experience, I'd say forget testing a three year old, it's just too much hit and miss. Four might work. 4.5 might work even better, but it appears Thetis too late for you. And yes, no matter how well you think you know your kid, testing may have surprises in store. Knowing is better than not knowing.
