Ooh that's tough. If you try to hit all five houses, you'll be spreading yourself too thin, spending 30-45 minutes at each house, and that's not enough time for you to get a good feel for the house or for them to get an idea of whether you'd be a good sister.
Use the time leading up to rush to maximum advantage. Get to know women in all the sororities holding informal rush. Maybe that will help you pick two or three groups to really concentrate your efforts on.
Good luck!
