DH and I did a pre-sale of VWL on the first day that they were available for sale, sometime in late Nov 2000. Anyway, we signed all of the papers, gave our down payment on the day we signed up. However, loan payments and dues payments didn't start until the month after when closing was supposed to be (Jan 14, 2001). Our first payments were in February. Also, we could make ressies with our points, but the ressies had to be after the closing date of 1/14/01.
My guess is that if they do some pre-sales of BCV, they will do them in a similar manner. You will sign the papers and give them a downpayment, but no more money is due until after the actual closing and release into the DVC.