25 is a good rule of thumb because typically your growth plates are fused by then and your hormones are balanced out so your body knows what normal baseline is. Before that you are at risk of fusing your growth plates prematurely and your hormone levels not getting in sync. I know most people think their growth plates must be fused at 17, 18, or 19 because the have stopped growing taller but that has little to do with it. Look at pictures of someone who is 18 then again at 25 and you will see a big difference. Maybe they are the same height but most fill out, broader shoulders, fuller rib cage etc. Do you really want to risk loosing an inch or two in the shoulder or chest department?