There seems to be much discussion on this forum about "playing too early".
IMHO.. as long as the kid can keep score and is courteous, fair, can call lines correctly, etc...they are ready. You are just training them for one more aspect of the game. it is actually hard to simulate.
Tournament play is such a different, mental
aspect to the game: shaking off unfair calls, loud, obnoxious onlookers, brand new opponents, the opponent's parents...sometimes cheering at your unforced errors. Mental toughness... Hard to practice that outside of the real thing.
All kids have something to work on. Most adults do. We just keep plugging along
There has been some debate (on forum) of current top juniors hitting an eventual success ceiling if continued to be allowed to compete without having all strokes and parts of the game "ready", and funny this thread popped up, I just was watching this video this a.m....Azarenka, age 13 at the Orange Bowl. Who can me she doesn't have strokes to work on (including serve!). But early tournament play does not seem to have hindered her. (I know you have a boy, so slightly different strategy, etc, ...but the moral of the story remains).