Do you know if it is a lotto? Generally, you "rush" for the tour. That means first come, first serve, and the tickets generally go on sale two hours before the show. I would call the theatre and check. Also, if for some reason you can get in line early, I would still swing by the theatre when you have a chance. The amount of people in the rush line depends on the amount of advertising in the area, dates of the show, and local interest in show.
So, that was the Drowsy Chaperone. Oh, I love it so much. I know it's not a perfect show...but it does what a musical is supposed to do. It takes you to another world, and it gives you a little tune to carry with you in your head for when you're feeling blue. Ya know?