My oldest grandson "Shooter" started shooting handgun competition with me when he was 8 years old.
We competed in USPSA/IPSC, Action Pistol, and Steel matches.
He actually was pretty darn good and beat many of the men that he had to compete against.
He shot the Single Stack Classic when he was 9, this was before they used USPSA rules so there was no junior class for him to compete in, he loved it.
There was a write up about him in the junior section of Front Sight magazine.