The thing is, though, the smells don't change all at once, they change very slowly over months and months and months. So maybe they can notice that there's a difference, but they'll still recognize them as you because they've been there through the entire process.
If, however, you go away for a while, they might not recognize you at first.
It's a similar phenomenon to how transition works with friends... those who are there through the whole thing will tell you that you don't look much different, where those who haven't seen you since before transition might not even recognize you.
My roommate's cats did admittedly give me some extended stares whenever I went out in "girl mode," but they still recognized me.
After about 11 months of HRT, though, I had to move away, and I didn't come back until I was full-time. Up until when I moved, despite being on HRT for almost a year, my roommate's cats never seemed to notice. They consistently snuggled up and begged for attention from the both of us about equally as much. When I came back as a girl 5 months later, it took them a half-hour or so to warm up to me again. (They're really nice cats, though, so it never takes her long.)
