While I respect everyone who enlists and doesn't go the ROTC route, that is NOT the preferred route if you have the grades to get into an ROTC program. Get a degree with ROTC and then join as an officer.
Is he a senior in HS? Then he is late for ROTC for starting college in 2020. If he is a junior, timing is great and he should do his research on how too apply for the scholarship(s) and get going this summer.
While it is geared for the service academies here is a lot of good info on ROTC as well (which is often the plan b) for service academy applicants).
https://www.serviceacademyforums.com/index.php?forums/rotc.27/
Best,
G