I want to correct a few misconceptions to start.
HRT is the first step in transitioning medically. Gender affirming surgeries are not done until at least 1 year of HRT, but usually more. The way you said pre-op first, then pre HRT made me think you may have a common misconception about the order of events. When I came out to my supportive parents, I did have to correct and reassure them that no I hasn't already visited Dr. Dick Guillotine.
Also I rarely hear trans people say pre-op. We use the term bottom surgery. Pre implies the surgery is necessary or inevitable, which it isn't. Some trans women choose to never get bottom surgery which is fine. Others get it and that's fine too.
The medical term in the DSM is gender dysphoria. Dysphoria as in the opposite of euphoria. Dysmorphia is a very different thing, it's the mental disorder where you're obsessed over a perceived flaw in your appearance. Very different thing. Dysphoria.
Good luck on your date! Be kind, get to know her as a person. Only discuss trans things if she brings up the topic. I have never had any issues with those who are kind and supportive but uninformed on trans issues. I just get annoyed at having to give the trans 101 lecture to every person I meet.