You should look into your school and see what they have for gifted students. Some schools have intensive programs and others only have a one hour/week pull out system. As for the Psy's comment..You gain nothing but knowledge by having your child tested. And if you do through the school it will cost U nothing.
However, I would recommend at least waiting until later in the year when your son is comfortable in school and confidant in himself and his abilities.
As for K, my HG daughter loved it! K teachers are usually a rare and wonderful breed. You may indeed be supsrised!