This is a topic near my heart as I'm at nearly 6 months myself. To be honest, before the HT I was plain bald in the front and now I'm happy, so it's almost surprising to hear that so much more is to come.
I was hanging out with some friends I haven't seen in a month or two 2 nights ago; two of them knew I had a HT, and others (friends of friends) did not. We were talking about how much my hair is growing in and after a while, one of the other folks went "what happened to your hair before, did you shave it on a bet?". When I told him I had a HT 6 months before he was genuinely surprised. He couldn't tell.
I've been getting similar reactions from other folks. I never tried to hide the fact that I had a HT and never had a problem talking about it, so when sometimes the topic comes up those who weren't clued in usually go "no kidding? so this stuff actually works!" which is great.
If nobody can tell now, I don't know what's gonna happen in 6 more months!