Yeah I'm sure someone could sit down and do the math based on training estimates people have come up with, but I see both ways having benefits. ID first benefits are:1. Less weeks you have to train your SF at C which can be difficult 2. ID gives a strong elastic to IS which can be nice to set up early3. ID early will make your trainee a more viable defender throughout their training1v1 first (and ID later down the road)1. Maximum extra pops from youth trainer2. Set up strong elastics early on3. IS can even be a small elastic for training ID later4. Might be faster overall due to maximizing YT extra popsSo I think both are viable and like you said, it might depend on the player's height for what you decide to do.
1v1 Forwards, ID, OD, and then JS Forwards.