I am interested in joining Delta Sigma Theta Sorority Inc. but I do not know when or where rush will be held..?

I go to a private college and my school does not have fraternities or sororities, however the surrounding schools do. Is it possible for me to pledge through the other schools? I am eager to get back to school so I could pledge, unfortunately I don't personally know any Deltas that can "invite" me to do so, how do I go about pledging?