I think it will be a long time before preferred pronouns are a common part of an introduction. It's definitely not the norm. However, in the queer community, at least among my friends/acquaintances, it does seem to be pretty common. In terms of gender expression, I lean more towards the feminine side so I have never had issues with pronouns but one of my past partners uses neutral pronouns and that can be an issue. Among out friends and the activities we are involved in, preferred pronouns are a standard part of an introduction but in society at large they are often, as you said, greeted with blank stares. My advice: include preferred pronouns because 1. a little initial awkwardness is better than the incorrect pronouns and 2. the more we talk about it, the more widely accepted they will become.