Today at school, I was at a college and career fair, and I saw all the mainstream students, (those from the main part of the school, rather than the alternative school, although the mainstream school is for kids at risk of dropping out) and I met this girl named Isabelle who was graduating this school year (so she's probably 17 or 18) and I struck up a conversation with her and got her number....... How long should I wait before calling?