I am a recent grad of UNC. I did not go through formal recruitment but I did have many friends that did and some sophomores including my roommate sophomore year who transferred to UNC and then went through recruitment that fall. UNC recruitment is not as competitive as an SEC school but recs wouldn't hurt you but they are not required as a more competitive school. Recruitment always occurs the weekend of Labor day in the fall and there are some chapters that have informal recruitment in the spring. You can check out
http://www.uncpanhellenic.com/ for more information. Good luck on your transfer!