Bro this is a layup. I don't think you can mess it up too badly, just leave some mystery. Get her to commit to a meetup while she's horny and don't write too much. I would say "I'd call you my good little slut". If you do close the logistics of the date while she's horny, I find it helpful to not go for the confirmation (day before date is ideal in these situations IMO) until you've turned her on a bit. She might feel some way about getting that dirty over text, and if you go for a confirmation out of the blue, she could get scared off.