That's great he is looking for a team experience. Boy gymnasts rock
I have an 8 year old on team. He started pre-team at 5 (almost 6). Here are some tips from my experience and from reading on here...
Boys can start team gymnastics "late" (later than girls to be competitive) and still have a great and competitive gymnastics experience. This is because the men don't 'peak' in their muscular development until age 18+ and the elite men are still skill-building well into their 20's. So starting at 9 or 10 as a first year competitor on a team is quite common, even later. That said, the most competitive kids are usually starting some kind of pre-team around age 4-6. But a later starter can catch up since the competitive road is long for boys.
Boys are at perhaps higher risk than many girls for dropping out of gymnastics as so many other sports pull them away. Building a crazy-strong body from gymnastics training makes you better at soccer, football, baseball, track, etc., and by the time gymnastics gets more serious (requiring 4-5 days training a week) many boys realize they cannot continue to balance gym and their other favorite sport, and drop gym. For this reason, the TEAM at the gym is key. The boys need that team-bonding to keep them in the sport. Look for a gym that has older boys on team to look up to, and enough younger kids (your boy's age) to bond with. How your son relates to the Coach is also key. Try out a program to see if the coach brings out his best and makes him feel good about himself, yet is also firm and provides structure (kids not running all over the place doing dangerous stuff).
As for hours, your son might start on pre-team (or possibly in a level 4 group if he has developed good skills from Rec). Likely pre-team is 3-5 hours per week, and will go up from there. Roughly, Level 4 (the first boy's level for most gyms) might be 6-9 hours of practice per week, level 5 might be 6-12 hours per week, and level 6 10-14 hours, etc.
Note there is not currently an "Xcel" type track for boys, so unless you have something regionally that is unique, there is only the JO track, which is usually higher commitment (hours-wise) than girls Xcel.
Gymnastics is soooo great for boys! Good luck finding the right fit!