May 27, 2020
Should he disclose this info when he applies for college since he will be turning 17 just when applications are due? Should a teacher or guidance counselor mention it? Would colleges even notice that he's young for grade?
Coming clean about your son's long-ago skipped grade probably will neither hurt nor help but--if anything--it will be the latter.
Will colleges even notice if it's not mentioned? Back in the days that I reviewed college applications, my boss trained her staff to be "detectives." So, yes, I did periodically note that some candidates were not born in the same year as the majority of others. Often this discrepancy was explained; sometimes it wasn't. When a student was younger than most of his classmates, I would look carefully at the transcript to see if the student had missed a year of high school or was trying to enroll in college a year early. If this wasn't the case, then I assumed that the student had started school very young or skipped a grade early on, and I didn't give it any thought beyond that. In other words, no biggie either way.
But occasionally, a teacher or counselor (or sometimes the applicant--usually in an interview) would mention an acceleration years back. I think that it worked at least a tiny bit in the applicant's favor to see a younger student who had jumped ahead and still done well.
When a student has skipped a year of high school or hopes to graduate early, admission officials are apt to scrutinize the application very carefully to make sure that the candidate is sufficiently mature and that the reasons for the hurried high school career seem sensible. But in the case of a student who skipped a grade well before, there shouldn't be any extra scrutiny.
So, bottom line: Not every admission official will notice your son's age, and those who do probably won't care one way or another since his transcript will indicate that he spent four years in high school. However, I see no down side at all to explaining his background to admission committees.