[quote=@Guardian Angel Haruki]
<Snipped quote by Lewascan2>

I'm thinking they probably met when Ciel was in late Middle School to Early High School considering the three year gap, and Bartholomew appeared during her college years.

Ciel was up for trying new things before Bartholomew, and realizing that it's easier for him to connect, so she would have been more than happy to try out Tabletop RPG if she had the invitation. After that, she would definitely stay connected with him online, until Bartholomew intervenes. 
[/quote]

Read my mind.

I would say for maximum dramatic impact from Barthalomew's interference, they met in high-school, yeah, and that way, they'd have been able to know each-other for 3-4 years before Ciel hit college and Asshole McSmarm entered the picture to cut her off from everyone else.