Well, important question: did she give you her number or was it you who asked her and then she gave you?

If it was her initiative, then why wait? She's probably just expecting you to show interest, so you should call as soon as possible! Not sure what time is it there right now, but maybe ring her tomorrow afternoon and ask her out for tomorrow night?

That's what I would do, though I was never so lucky that a girl would just give me her number, I always had to work hard and sometimes it wouldn't even come to that.

Anyway, I'm an older dude and that's how it worked when I was younger, not sure how people do these things these days... maybe you better wait for more advice.