Just remember as well that the Feb 1st deadline means that you have to join up as of Feb 1st.....not just contact
DVC Sales. I just verified that with DVC Sales. The final signed paperwork wouldn't have to be completed by then, but an initial payment over the phone with the paperwork in process needs to be completed by Feb 1st to get the discount.
If you have questions before you go to sign up, ask here, or get a referral and contact DVC, but do it quick. That 15% off is a great deal, and although I am sure they will have new discounts in the future, I highly doubt it will be as good as this one.