can you miss a day of recruitment

Girl, you are FINE. PNMs before you have missed more days than that and ended up in great orgs. After you send in your absences to your Rho Gamma, my advice would be to really make the best impression you can at Round Robin, and tell the girls you talk to in each room that you're missing sisterhood round, so you're eager to learn as much as you can that day. But definitely definitely don't let missing a day of recruitment keep you from being a part of a Panhel org for your sophomore year. OR, if pref night comes and you really feel like missing Sisterhood has messed up your chances with your top choice orgs, then just give it another year and try again! (PS it's a nasty rumor proliferated by trolls on this site that juniors don't get bids or are out of favor, so if for whatever reason you do decide to wait, seriously, you're fine). Best of luck!