First welcome to this website. You will find more information here than you can digest. You are early in the process. So I would think first, find someone reputable or a showcase that can give your son an idea of where he falls talent wise. I saw you were from the midwest. Perfect Game and PrepBaseballReport both do that. PG is more national, they are excellent at what they do and can be pricey if you are on a low budget ($500Plus depends on which showcase you go to). They will let you know where you son is talent wise. PBR is midwest basically (Kansas, Wisconisn, Illinois, Missiouri, Indiana, Kentucky, Ohio, Pennsilvania, West Virginia). They are less expensive but you don't get a "rating". You do get to see compare son to others in your region. Niether will tell you (your son is D1 or D2 or Naia), but you will get the basic idea. If you think your son is D2, he is probably D3 
. We all have rose colored glasses when it comes to our child. I know I did. The best way may be find someone locally who is a scout of MLB or someone who does instruction who has the background to tell you (I learned that from here).
I would find him the best team he can play on (not be on, but play on). The big year for that is summer between Junior and Senior year. If your son is big time D1 (like top 10- 15 in your state since you are midwest), then recruiting will start this time next year. D1 summer between Jr and Sr year will be the key, then D2, and D3 and so on. Most D2 and D3 are really heating up in Ohio right now, but being that it is 45 degrees right nowout, the summer is the key.
I would target 20-25 schools he is interested with his major if he knows. Have some at every level. Research coaches and rosters and have him email them and introduce himself. If you get the opportunity, go watch in spring, some at every level. I think you will get at least some idea where he might have an opportunity.
I wish you and your son the best of luck. Recruiting is a roller coaster. Enjoy it, it goes by very fast.