When I was a rho chi, rush started pretty much the second that freshmen arrived on campus. There were summer programs for freshmen, so I had to deaffiliate from the last day of spring finals through the end of rush. I wasn't allowed to talk to anyone affiliated with any sorority - which was a little difficult since I was on campus, and particularly during rush since one of my suitemates was in a sorority, but I had plenty of unaffiliated and male friends, so that was ok. And we did some rho chi activities during work week, so we had the chance to bond a little.
(Sidebar: I boxed up all my sorority stuff for the summer. It is amazing the amount of stuff you can accumulate in 3 years
)
My school is now going to deferred rush. My understanding is that, during the fall, rho chis can't be seen publicly with more than 1 or 2 sisters, but they can go to closed events, like formals and retreats. Once everyone returns from winter break, rho chis can't interact with affiliated women at all. Hopefully this will be a good balance between making it difficult for freshmen to figure out the rho chis' affiliations and allowing the rho chis to have some level of interaction with their sororities during the fall.