In my case, with sorority #1, I met with the chapter representative who promptly invited me to a chapter get-together a few days later. Sorority #2 also invited me to an event soon after I met with the chapter president, but I wasn't able to attend one of their events until about a month later. The president of this chapter sent me an e-mail whenever they had an event.
Granted my experiences were a little unusual in that I didn't have to do much follow-up at all, but I think it's safe to say that if people are taking time off for the summer, it might not be a good idea to pepper them with e-mails or letters all summer long. I think one letter sent before the break and one letter sent soon after they reconvene is sufficient.
Now go somewhere and sit still, young lady!
