How long did it take to notice it? Maybe 6 months for me? I've been worried about diffuse thinning ever since I turned 17 pretty much, and my hairline (while always mature) started to slowly but surely recede @ age 16. Ever since that initial recession, I've been noticing my hair slowly waning (while nobody else has). However, I've always been very VERY conscious of my hair, simply BECAUSE of the mature hairline. There's pictures of me in Grade 9 and 10 already losing my hairline. I mean, some of you guys post pictures of the hair at your temples turning into baby hairs, etc., but pictures like that were all over my yearbook in my freshman and sophomore years of highschool.
So basically, I'm a norwood 1.5-2 maybe (probably 2), and I lose what looks like 30-50 a day (just showered, saw 3 on my hands, styled with harsh gel before that which would pick up some hair, saw none). It's not just in the hairline areas. As to who has a better chance with finasteride? Who knows, I won't go on the stuff yet, not ready for that hyper-hypo-androgenetic-psycho-reflex garbage just yet. Plus, I kinda like getting boners.
Hope SOME of this helps!