It will take a minimum of 15 days before any correspondence. I interviewed 9/8 and they sent the letter on 9/23, however because it was lost in the mail I didn't get the second one until 10/10! Essentially two weeks to decide, then they mail.
I interviewed on Friday, 11/11. Susan Hanson said that the committee meets weekly on Wednesday to decide on the previous week's interviews. Then it takes two weeks to get a letter out. So worst case is 3 weeks.
Another question: Is there a deadline to either accept/or not their offer if you do get one from Western? Do they give you a limited time span to decide?
Yes, I think they do give us a limited time span, but I think it's longer than what other schools may give. I got my letter in the beginning of November, and the deadline for my deposit was December 1st. Good luck to you! I enjoyed my day there....it's a good school with lots to offer.