You can't put a rule on something like this, you've been watching Swingers too much.
Myth 1: Every guy calls the next day, by waiting 2-3 days to call, you become unique, something she's never seen before, it will make you look like a challenge, and the b!tch will love you for it.
FALSE. Every guy I know waits several days before calling. Waiting several days to call MAY have been unique once, but right now, it's a social norm. Every guy does it, and every girl knows it.
Myth 2. Calling the next day will make you look desperate and will scare her off.
FALSE again. If a girl is interested in you, calling the next day wont scare her off. If she's interested in you, she will be happy to hear from you. In my personal experiance, this has been proven true. I don't follow this rule, I'll call the next day and still hook up.
The only time a girl will be scared off and think you're desperate is if she wasn't into you in the first place. In which case, waiting several days wouldn't have changed sh!t.
My opinion?
Call her 3-7 days later if that's what works out for you. Each person has their own different style of the game, and what works for some may not work for others. Personally, I don't follow a rule that is written in stone (except never take a cheater back). If I feel like calling her the next day, I'll do it. If I'm busy and don't have time for it, I'll call her when I have time. One thing I wont do is use something that doesn't feel natural just to raise some b!tch's interest level. I approach at least 1 girl a day, even when I'm in a relationship, just for practice. It's her job to raise my interest level, not the other way around.
IMO, that's why so many of you DJs fail and end up coming back here. You still see the world as women qualifying men, instead of men chosing women. Even though you know most of the game, you still don't have that attitude that places you higher up in the foodchain then females. It's the woman's job to tame you, not the other way around.