When my son was twelve he picked up the ball in March and played through LL states in August. Concurrently to the LL season he played in a USSSA Sunday doubleheader league. He didn't take paid lessons until he was sixteen other than one lesson where I told the instructor what I wanted him to understand. He was well coached in LL and travel through age fifteen.
Winter was for basketball until he decided to give it up for baseball winter workouts when he was a high school soph. I don't think he would be any further along if he had all kinds of lessons when he was twelve. He does have a live, fresh arm from lack of emphasis on pitching until high school.