Hey. I am personally friends with a number of people who stutter. It’s the neshama that matters, not outside appearances/habits, at least in my view (Remember that Moshe Rabeinu had problems with speech as well, that didn’t stop him from being the biggest Navi ever). Whether to say or not to beforehand… I’d say it depends on how you think it would affect your date. Good luck!
Bhatzlacha, Dovid