DS received an offer for a Type 1 HS AFROTC scholarship, so I can only speak from that perspective, but I can share our experience. We just got back from visiting the Embry-Riddle Aeronautical University campus. DS will have 33 hrs of dual credit college courses by HS grad (May). ERAU agreed to accepting 23 of those as direct transfers (more than we were thinking they would). As previously stated, all campuses are likely to have different policies, but his schedule at ERAU will be rigorous enough, each semester, even with the transfer credits, that it won't affect his full-time student status. All it will do is allow him to not reach "unbearable" state with his course load. And, in a few instances, it will free him up to take a few alternate courses in situations where he would have had to choose between two elective technical courses, both of which he would have wanted.
He will still have to complete 4 years, and he will still have to remain full-time status, but now he has some latitude on course choices. He also had/has the opportunity to bypass his freshman calculus, due to his AP calc class he's currently taking, but he chose to forego the credit and take it anyway, because he is taking some REALLY difficult classes at ERAU, and feels he could benefit from retaking the class at ERAU, as it will act as a stepping stone for a lot of his classes afterward.
He also had/has the option to skip his first year of ROTC GMC courses, by virtue of his Civil Air Patrol Amelia Earhart Award, but has opted to not do so, after visiting with the ROTC detachment leader. The leader stated he could do so, and come in as a "Super Freshman," but it would complicate things, regarding his class ranking with ROTC (which is a potentially different ranking than the one the college recognizes...i.e. you could be ranked a junior with the college but be ranked a sophomore in ROTC or vice versa. Your scholarship is affected by your ROTC class ranking, not the college's.). It would mean that he would have to go through Field Training the summer after his freshman year, instead of his sophomore year, and might complicate things, in terms of his commission and when he would be required to report as active duty (potentially leaving him obligated to report before he earned all his credits for his degree). He said it could be done, but he would advise just going ahead with the full 4 year ROTC plan, to keep it simple. So, if he accepts the offer, that's what he intends to do. He is currently trying to decide between AFROTC and accepting an appointment to the AFA (just found out two days ago), but is leaning toward ROTC.
I don't know if his situation provides you with any guidance, particularly given that you are referring to AROTC, but I hope so, since they work generally the same. The short answer is that, if you are planning on a highly technical major, it is probably unlikely that your transferred credits will negatively affect your ROTC plan, and may actually help give you some breathing room/latitude on your academic schedule, but don't plan on it shortening your overall length of time in school. But your ROTC detachment would be able to say for sure.