I agree with Cat. I did not start until 12, although I played other positions.
It is adults who have issues not being able to compete, with balance and "not pushing them too much." It can be done, it is in our attitudes.
You DO NOT have to play and practice every spare minute to be better than the competition. You just have to have quality practice minutes, provide for good rest and build confidence.
Trust me if you have to do so many reps at 8, by the time you are 15, you have no more reps to give. I see it all the time. Never mind having something in the tank for college.
I totally agree with the QUALITY practice minutes. You can spend hours everyday just throwing the ball....it's the time spent perfecting the correct muscle memory that counts. That doesn't take hours per day. It also keeps them loving the FUN of the game.