It was probably closer to 2 or 3 months when I first had noticeable booblettes. But it was probably at about 4-6 weeks when I started to get very tender nipples.
With regards to orientation and sex drive, my drive did indeed dip a bit after starting HRT (I'm at 19 months now). I've always been bi, but it seems like what I find attractive fluctuates. I was VERY bi shortly after starting HRT and these days I'm leaning more towards finding women more attractive these days.