That rule does not apply to reservations made for a stay at a
DVC resort.
Subject to availability, you can book your home resort up to 11 months prior to arrival. You can book a non-home DVC resort up to 7 months prior to arrival.
Did you buy from Disney? If so, you probably got 2007 use year points. If you aren't going to use the 2007 points for a vacation that happens before 12/1/2008, you'll need to bank them asap. Normally, the banking deadline is July 31 for a December use year, but DVC makes an exception for new buyers.
The rule of 4 is for selected non-DVC resort reservations. For example, with a December use year, you couldn't make a points reservation for the Grand Floridian after July 31 if your trip is going to BTW, there is an extra $95 fee to make most non-DVC resort reservations. (Some exceptions apply). But you could make a reservation for a stay at the VWL or any other DVC resort as long as space permitted.
Use year can be a tricky concept for new members to understand, especially if they have a December use year. Here's a thread that may be of help to you:
Understanding Use Year
The thread is old, but the concepts are still the same. The only difference is that the booking policy has changed since it was posted (from 11 / 7 months prior to check out to 11 /7 months prior to check in).
Welcome to the DVC Forums and congratulations on your purchase!