A few months I think. Once I start taking my shoes off in his vehicle and tucking my feet into the corner of the dash I really like him. When we go out to dinner and I'm sitting with my feet tucked into the seat, smiling, relaxed, laughing. You know real laughter that only happens when you are truely at ease with someone. I'm always giving him the keys so he can drive (which also means I trust him to get me where ever safely.)
Hmmm, if I wear my glasses instead of my contacts, because I'm super blind and I feel vulnerable in my glasses. If he catches me singing... really singing, because that's something I love to do but I'm rather shy about. When I walk around the house brushing my teeth and I don't care that he's there. I wear less clothes, something like just a tshirt and I'm comfortable with him seeing me like that, just walking around, maybe with my hair messed up from sleeping.
When I complain about something. Most of the time I try to keep things to myself, like I'm freezing or whatever... but when I'm comfortable I become more vocal. Oh most importantly when I can't fall asleep without him.
Edit:
It's not about putting on an act. I don't act like someone I'm not, I'm just not relaxed. There's a big difference. Relaxing around someone makes me vulnerable, walls are great for keeping them out. It's an automatic reaction to turn into a Stepford. I'm not sure why I do it. Which is probably why I only date guys that I'm friends with first. Someone that I already feel moderately at ease with. Otherwise I'm knocking over water glasses, dropping things, stepping on his toes...