Hey big black.
I have a pretty bad receding hairline (resulting in a large forehead) and some noticeable loss on my crown area..
I have been on propecia for about 8 months and have definitely seen some improvement and regrowth around the crown area. To be honest, Propecia has not really helped my hairline a whole lot (in terms of regrowth - it's definitely maintaining the remaining hair I do have tho.)
Depending on your age, I would 100% recommend you get on Propecia ASAP. If not your hair will just get worse and worse.... If you keep on waiting without taking any action (like I did) chances are you will NOT be able to regrow what you have lost. Prior to starting on Propecia, I was on Rogaine for about 4 years, however my hairloss got so aggresive even Rogain began to lose it's effectiveness. (I'm 24yrs old.)
In my opinion, it all depends on what type and the degree of hairloss you have. If your a diffuse thinner, chances are Propecia will wonders. If your a receder, in the the majority of cases propecia does not work that well (prob maintains at best.)
If you do decide to start on Propecia.... just expect to maintain. Anything else (i.e. frontal regrowth) is a bonus.