I haven't lost a whole lot but pretty much every other day something happens to make me think I'm smaller. Perhaps it's wishful thinking.
Overall I think I look the same, but little things I definitely notice and pretty much focus on -- like the fact that I can see collarbones, for instance. And I'm kind of obsessed with flexing my leg muscles in various positions and feeling the solidness I've been creating there. And sometimes I'll put my hands on my waist and be surprised at what I feel (either due to change in size or developing muscle). Occasionally I'll catch myself in the bathroom mirror and think, hm, my stomach looks a little smaller, or my hips look a little slimmer. I don't really care if this is actually true or not, but believing it myself has been great motivation for me.
Generally I'm just loving all of the changes I'm finding in my body. From the very outset of starting to lose weight I've been staying focused on what I can tell is changing. I don't really mind if no one around me notices, and most of the things I notice are very personal (no one aside from DH is allowed to feel my leg muscles!
). Sooo, to answer your question, I've been noticing since the beginning, in many little ways!