What can I expect from Propecia?

So I am 19 and clinically diagnosed with Male Pattern Hair loss (so happy!). No bald spots, just thinning on the temples and crown area. I started Propecia today and I wondered what I can expect in terms of results. I guess there are a few factors to consider.

  1. Considering how early my hair loss started, I guess I can expect it to be pretty aggressive. I can’t tell if my older brother (About 26 months older) has receded yet but I suspect he has. Anyway, hair loss that starts early tends to be more aggressive, and therefore harder for drugs to combat.
  2. Having said that, I do believe that I took action as early as I possibly could have, which hopefully will give me some advantage.
  3. I did take a very low dose of Accutane, an anti-acne drug that some have said quickens the course of MPH. I took it unprescribed (probably illegally) for acne that a doctor wouldn’t have even looked at. Whatever consequences of that are entirely my fault, I know!
  4. My Dad, 65 has lost most of his hair at the top. I have no idea what he looked like age 19-20, I have looked for photographs.

All in all, I’m bulking myself up and am prepared to be shaven by the time I’m 25. I’ve been told that I have an unusual face and head shape, so maybe it will be a distinctive look when I shave (in a good or bad way, who knows?). However, can I expect Propecia to work for that long considering my circumstances?