There isn't any good age. If he enjoys it, then it is the right age! You mention that he is very hyper. This can help burn off that hyper-ness. Later on, it can help burn fat and gain muscle.
So yeah. Let him loose! If he doesn't like it then try other sports!
Grand opening was pushed back once again, we'll just say it's TBA for now. We are still waiting on the completion of some custom development that has been in the works.