If you're wanting to know how quickly you can make a reservation, it can often be done in the same phone call in which you agree to buy--later that same day at worst.
You'll still have to sign and notarize a number of documents and wait for the closing to occur before there is actually a deed in your name. That entire process could take several months, and is dependent upon the resort's construction schedule. And it will probably be several months before you could make your first stay--ask your Guide to confirm the exact date.
But one of the benefits of buying direct is that you can at least get a reservation on the books almost immediately.