What Zydecocruiser said is correct. I just got back from a 7 day cruise on Conquest and there were plenty of advertisement sent to your room about such promotions.
The promotions also pointed out prices and cabin category openings on upcoming holiday cruises like Thanksgiving, Xmas, New Years, and Spring Break. I was very interested in the Thanksgiving week cruise that I could have paid less for than my mid August cruise. Unfortunately, my work schedule didn't allow me to commit to it...but it was extremely tempting.