Have to agree with the posts on here. Start them as young as possible. We take them in from 4 year old and it's all about getting kids enjoying playing the game and having lots of touches of the ball. My 6 year olds are now playing fun 4s tournaments and some of the shouts from the parents and coaches are ridiculous, as are the whoops and screams when a goal is scored. The ethos of the club will play a big part in how your son is developed. I know that I pull any parent up who tries to coach their son during a game. We ask parents to actively encourage by clapping or shouting well done but the coach will talk them through where they need to be on the park etc. I would suggest that you go and view a couple of clubs and look at their training sessions and view how the coaches interact with the kids, ask for their visions and aims as a club and gauge your choice from there.