train the youngest guy with them for now. He can be a nice backup PF. If you're training JS first, you can train all of them at the same time though, until next season at least.
Yes, you'll need to train JS for two seasons to get it to marvelous for that guy, but you shouldn't start that way. Get it to proficient first, train his other skills, and when those are good enough, come back to training JS further. For now, having him shoot proficient jumpers seems good enough, for DV anyway, but there will be a time when you'll need more.