It's never too early to get extra help. Most of those guys giving lessons aren't there to teach curveballs and stuff. They will just focus on fundamentals. The only drawback to some of these guys is that they try to make every kid do things the same exact way, like robots. I'm a firm believer that most of the time, it is a comfort thing. For example, in hitting, you'll see lots of different stances, but in the end, in order to hit consistently, everyone gets to the same spot (back elbow to the belly button, hip rotation, hands inside the ball, etc...). To think everyone can stand the same exact way is crazy. I think it's comical when I hear little league coaches screaming "get you back elbow up" to every single hitter. Sure, it works for some, but not all. Look at the stances of MLB and NCAA players. Lots are different, but in the end they end up in the same place if they're doing things right.
I believe if it's not broke, don't fix it. I've seen ugly stances with good production and I've seen beautiful stances with zero production. It's all where you end up.
Pitching is the same. If he's throwing strikes and hitting spots, a pitching coach may not be needed. Could a little tweak here or there help? Maybe. I guess it depends on where Mason is at this point. For example, if he's not reaching back enough and you're constantly telling him to and he doesn't change, maybe he needs somebody else to tell him. I'm in that spot with Klay. I might as well talk to the wall.
Or maybe Mason is throwing across his body. Somebody else may pick up on that. Or maybe he's not sitting on the back leg and driving to the plate.
For the most part, going to an instructor can't hurt, just beware of that one that starts changing stuff before he even sees Mason throw. That's the guy that wants a robot and that's the guy that will waste your money. And, if he wants him to throw curves, just step in say "not yet". Changeups? Do it! Curves? Not yet. If he can change speeds effectively and keep the ball down, he will dominate little league and can even get by in HS with that. Keeping hitters off balance, like a whiffle ball game, is key.
