I am not really passable and fully out yet, so I don't have too much experience with this. However, my close friends have used female pronouns with me for a while. Honestly, it always felt natural and I enjoyed it. Though, it does get a little awkward when they say it in public and I am in boy mode. I have seen people take a good look at me in those moments. Also, I have gotten ma'med on the phone a couple of times at my old job. That always set me back because I wasn't trying to pass and don't believe my voice is very feminine at the moment. Still, hearing male pronouns has always bothered me and I can't wait for it to stop. So, all in all it is pleasant when it happens.
While it may be awkward in the beginning, take this as a big sign that you are passing really well. That's a good thing in my book.