Such a classic question and a tricky thing. If you call the next day they might think you're desperate, but if you wait too long that intial attraction might begin to wear off. I think the perfect amount of time to wait is 2 days. If you got the number on a Thursday night, give them a call on Saturday.
Go ahead, have some fun
youwishyouknewover a year ago
I agree, wait two days. BUT make sure to say "To be honest, Ive been thinking about calling you, i just didn't want to rush, but its hard to help myself." Or something like that, be creative, a nice honest line there will help start things off more comfortable, on a honesty level.
No need to hold your feelings back, let her know, i bet she'll like it.