For the most part it really depends. But if you start calling the very next night, you might end up calling every night or making plans whenever you get the chance. You have to have better things to do than just await the next date with this girl. The general rule is 2-3 OR MORE. I used to wait a whole week. Not just because I was playing the game, but because I was busy and had other stuff to do as well. She never lost interest and in fact, she started to really miss having fun with me which made it sweeter for her when I did call.
Don't call and just talk about the weekend and stuff. Only use the phone as a tool to setup the next date. You'll have more to talk about on the date and usually she'll be more excited if she hasn't spoken to you in a while. I kept my dates to 1-2 every week with a single girl. I used to hook a couple girls at once so it followed a routine pattern.
My advice is don't call, at least for another few nights. And when you do call, tell her you're free on X day and that you wanted to do X thing and you want her to come along. Simple and to the point.