Thanks LisaRex. I actually have not booked using SOs before. How does one calculate exactly 8 months ahead, down to the day?
Add 4 months and subtract one year from your desired check in date.
Example: If you want to check in on April 21st, 2012 you'd call at 9am on August 21st, 2011.
***
Also note that openings at WSJ tend to go very quickly. It's best if you don't have a reservation already in place (e.g. at your home resort) because the CSR will need to go in and cancel your existing reservation before booking WSJ. By the time they get done with that, the WSJ week may be taken by another caller.
Don't forget to check Friday and Sunday check-ins either!
Also, FYI, if there is more than one unit available, know ahead of time which one you'd like. The Hillside villas are more removed from the main resort, and have their own pools/BBQ. And the parking lot is very close to the units. Bay Vista Villas are closer to the main resort and you feel more connected to the resort, not just because of its proximity, but because you use the amenities of the main resort (e.g hot tub, pool). The big downside with Bay Vista units are their distance from the parking lot. Hauling snorkeling equipment up that hill can get old.
***
My experience booking WSJ:
The first time I tried to exchange to WSJ (for January 2010), I was able to get the exchange on my first call, albeit for a Friday check-in. The CSR expressed shock at seeing it, so it was a pleasant surprise for both of us.
The second time (for January 2011), I was never able to get in, despite calling several times a week for months. 3 bdrm units were available, but no 2 bdrms.
This last time (for January 2012), I was shocked to hear that there were several 2 bdrm openings for the month of January -- which is high season on St. John! I was even able to change the dates of my reservation twice (at a cost of $29 each IIRC) -- ultimately to a Saturday check-in date that matched a held frequent flyer award reservation.
I'm honestly not sure what conclusions you can draw from all this, but there you have it. No matter what, your best bet is always to call in at 9am 8 months out and keep calling, if needed.
P.S. When you do go to exchange, please report back to let us know how it went.