When I was in chapter, we had two girls observe the Sabbath because they too are Seventh-Day Adventist. One of them's my pledge sister!

Initiations usually took place Saturday mornings, but we moved it to Saturday evening after sunset to accomodate them. We kinda had to, for reasons I can't say because it pertains to Ritual. Whenever they'd miss an event because it fell during the Sabbath, they were not penalized or fined.

Since you're not in a sorority yet, it's best to just focus on recruitment first. However, I do agree with the others who have said that it really depends on your school. Has the recruitment schedule been posted for your school yet? Do any of the recruitment events fall during the Sabbath? I wouldn't worry about it just yet. When you meet your Rho Gamma (Recruitment Counselor), this would be a good time to ask her about members with religious observations. Chances are you won't be the only one.