I am all for people living their truth and being comfortable in their skin. That being said--it can be confusing. Hopefully, the person is understanding, gives grace and is patient. It's still fairly new. Not everyone is going to grasp it, remember it, or even like it.
My biggest gripe...well, my ONLY gripe, really...is the fortunately very, very few people who are going by pronouns that seem to clash with their appearance, don't specify what their pronouns are and then get mad if the wrong pronouns are used. I don't like to assume. TELL me your pronouns and I will do my best to use them 100% of the time but please be gracious if I slip up once or twice...or misgender you right off the bat because you didn't specify a gender.