Question about Propecia.

[winkywoo]

Hi guys. As the title says I have a question about Propecia. I'd like to know how long it exactly works.

Say for instance a 19 year old who is a nw2.5 with pretty agressive MPB didn't treat his balding and just left it alone. Let's say he would be a nw4 by the time he's 24. If he jumped on the big 3, when would he expect to be a nw4? I know obviously nobody can give me exact answers, but Im asking roughly. If they were a good responder, when would the be a nw4?

Thanks!