the younger you are when you learn something, the better you get as you get older. that's why most top athletes in any sport started when they were in nappies (slight exaggeration). champion boxers, world class footballers, etc were all younger than 9 when they started.
tbh i would try and get him interested in a sport, than a games console, and focus all of his attention on that. will get him used to living a healthy lifestyle from a young age. this is the main problem with the obesity epidemic hitting the world, parent's aren't pushing their kids in the right direction from an early age. then they wonder what has gone wrong.
im not saying don't let him play the console, it's just that it would be much better if you focused him on something a lot healthier like playing football for real than sitting on a couch pressing buttons, what he learns from an early age will dictate his life when he grows up.
if he is 9th prestige already, etc this points to him playing the console a lot. now just your average gamer imo.