In your situation I would give him an hour per day (10 minutes is a very short amount of time to do anything fun or see progress in most games) then monitor the outcome based on your previous baseline , does he ask for extra time when its time to call it quit, do you see a negative outcome on his grades, focus and desire to play outside or with other toys, etc. Then simply cut back if you see any downsides with 1 hour per day. You should definitely play with him during that time if you can, it is a great way to bond with your son and try to change the activity during the week, like play lego with him instead of gaming and see what will be his reaction when a video game is no longer involved.

Video games are always good in moderation and there are definitely some great games for kids, exploring with him when searching for a new game will teach you a lot about about why he’s drawn to such and such game and this way you may be able to find other hobbies outside of gaming which are related to his interests.