Pick a few dates, sign up to Kayak and set daily alerts for those dates. You'll get a daily email with that days prices. When the price drops, jump on it.
Also, of you're a WJ rewards member, make sure you're signed up to receive emails for any specials. There was just one this week, and I got a great deal in August. Those were for travel until mid December. Maybe they'll have something for the new year.