I have never had a problem using the women's washroom since I started presenting as female. The first time was after a support group session in the city (an hour and a half drive away). I was on my way home, dressed in a nice skirt, and I felt the call of nature. This was before spiro, but I probably had had some coffee at the group or something.
I pulled over at a truck stop. Hell will freeze over before I go into a men's room in a skirt. I figured I'd be a whole lot safer in the women's room. So, I boldly walked into the ladies' like I'd done it a million times before. Luckily for me, no one else was in there.
It has been uneventful ever since. When I was part-time, I used the ladies' when presenting as female, and the men's when presenting as male. Now, it is the ladies' room every time. I have learned to carry on conversations in there. In the concert band, where everyone knows that I am trans, all the woman go in a group at the break, and I am included.