When Can You Call Someone After You’ve Just Got Their Number [Audio]?

My Intern Hazel was "holla'd" at by a guy and she took his number. She says he was cute and would consider calling him, but doesn't know how long she should wait. What are the rules of engagement?

The question is how soon is too soon. What do you normally do in this situation. Me and Hazel took to the phones... Here are some calls we got!