I think it's child-dependent. Can the child handle losing and winning with grace in other situations? You may also want to find out how intense the feel of the competition is. DS started competing in chess tournaments at 5. I really was hesitant, and there are still things about it that I dislike, but it's also been good for him. I noticed his grace and sportsmanship when he started playing a team sport--he handled loss and failure much better than many other kids who had probably not experienced a lot of this before. I would actually feel more enthusiastic about it if he were less good at chess. He has a lot of expectations on him.