if you'll make it is almost entirely up o you, how hard and smart you train.
I'd say immdietely start Olympic lifting. Squats, deadlifts, bench, cleans, pull ups ect..
Start to learn about biomechanics. Analyze the small players in the MLB who throw hard.
there's a lot of different people saying different things, some of which are completely incorrect. To avoid this, I'd reccomend only taking advice from those who use updated scientific studies to give advice.