I'm a 26 year old male, and haven't had any luck until now. I matched with a girl on a dating app and after a few days of messaging I asked her out, to go see a museum exhibit we're both interested in

But now I'm realizing I have no idea what I'm supposed to do, do I just vomit out information about Pre-Roman British Isles settlements? Do I let her start the conversations or should I? What if she doesn't show up? What if something happens and I can't make it? What if it goes really well? What if it goes really badly? What if it's all just a joke at my expense?

I'm trying to get ready for bed and every possible scenario is racing through my head, I'm worried I'm going to get so wound up I'll blow it

Edit: She stood me up, so I came home and just made dinner. I'm kind of weirded out about how lacking in any kind of emotion I feel right now