I won't lie to you-- it will be weird to some extent! If you go in spring, you'll miss your last months with your seniors; if you go in fall and your school has early recruitment, you'll miss all of the recruitment activities and all of your chapter's new sisters will be totally new to you! But don't let that stop you. You just need to be aware that it will be somewhat different.
Communication is very imporant. E-mail will probably be available to you, so use it! IM won't necessarily be feasible depending on when you can get online-- the time difference can be a real killer. Make sure to email your parents as well as your friends.
My boyfriend (now my husband) and I had to share my email account since he'd just graduated from school and hadn't gotten his own account yet. This was ten years ago, so we had to dial in from the townhouse we stayed in at Cambridge, England. sllllooooowwww connection. We would talk on the phone about once every two weeks, which was very often considering the cost. We also wrote actual snail-mail letters back and forth.
Make sure to save copies of any emails you send describing your trip-- they can become a kind of journal of your experiences. Keep a small written journal, too-- it's the kind of thing that you might want to share with a husband and kids someday.
Like I said, it'll be weird, but it's worth the weirdness! If you keep in touch with everyone, and stay interested in their lives, it'll be an easier transition.