I've been on finasteride for 7 months now, and I'm not sure if I've been through a shed or not. I think I was losing more hair around the 3 - 4 month mark - certainly there was more in the shower, but I've continued losing hair gradually over the past 3 months, and it now feels really limp, and it's much easier to see through in the light, more temple recession, and the back is much thinner.
It's hard for me to be optimistic because I don't think I've been through a shed, and then seen great regrowth, only to go through another shed... It's just been a gradual thing.
Reading posts about people not seeing any results at all until month 8 or even longer keeps me going though.