Hopefully someone else will correct me if I am wrong about this, but.....I believe.....
You can book now over the phone, but i don't think that next year's rates are out yet. When the rates come out, your booking may be changed to reflect the actual rate, if I am right about this. By booking now, you will be assured of the resort reservation, but not price. IIRC, they charge a premium price to book at this point. I'm not sure how close they come to the actual rates.
I would check on any reservations made now for next year when the rates are released this summer.