As you can see, there is a general concensus that 17 to 18 years old is about the right time.
I do not agree.
While I would agree that it is the right age for a lot of people, it could be terribly wrong for a good number of people.
The critical issue is that you must reach almost full physical maturity before the surgery is done. By that standard, I would not have been a candidate for surgery until about the age of 35 due to hormonal problems.
This is but one of the reasons why it is important to see an Endocrinologist prior to seriously considering surgery.
Prior to surgery, you need to establish the cause of the Gynecomastia (if possible) and be sure that your hormones are stable at normal adult levels. If this important step is omitted, there is a risk that the breasts will regrow due to other problems which should have been resolved but were not even checked. Liver function is another thing that the Endocrinologist may want to check.
No doubt there are some of us who could be good surgical candidates at even younger ages; but that depends upon their physical maturity.
It is important to realize that physical maturity and mental maturity are two entirely different things.