I think the question is how flexible you are, and what your priority is.
If being in a certain resort is a priority, and you want a certain category within that resort, and can afford to pay the rate offered, then I would book room only before a discount comes out. The discount may or may not apply later. You can make changes later, if you need to.
This would not be the best way to get a discount, because the more total bookings they have at a certain resort, the less likely they will include it in discounts. Also, if you have a reservation booked, in my experience, you are less likely to get sent a pin code.
If you are not picky about where you stay, but are more interested in paying the lowest price possible, you have more leverage, and can wait, IMO. As long as you aren't going in high season, there should always be something available- maybe even off site.
We always know where we want to stay ahead of time. In the past, we got PIN codes very early on and booked with them from the beginning. But when no pins came out for us this year, we knew we wanted to stay in POFQ in Aug., so we were willing to book with only a
AAA discount, even if it meant we would never get any additional discount. We are not free-spirited, "We will stay anywhere for a good price" folks.
For our January trip, we are booked at POR, because that's where we want to be, and will pay for it without a discount if we need to. If a really good discount comes out later, we may keep POR or even upgrade to BC. I am not willing to pay rack or AAA rate for BC. So no sense booking a room there now. Either way, I know we have a room already reserved for our trip.