No one in this thread can answer that. Your body is one of a kind and transition relies on a lot of things no one can really accurately understand (genetics mainly). A transition starting at 19 is going to be better than one at 20, at 21, 25, 30 so on so forth. You are going to be living for a while either way; would you rather take the risk of not looking perfect, or do you trust yourself enough to shove all the feelings down and see how well that goes?