I will also agree with Rich and OR.
Most of the worlds strongest and successful competitors in iron-sports have started at a very young age, many before 10yo. Age doesn't determine the extent of success, but starting young can bring him that much farther.
That said, some kind of base needs to be developed in strength, flexibility, conditioning and skill (coordination). Lots of bodyweight stuff as mentioned by OR is great. During this time I also wouldn't hesitate to throw an empty barbell/broom stick/pvc pipe at the kid and get him practicing the correct movement patterns of the key lifts... just don't load up on it until an "impressive" base is developed.