We just bought our AP's on 2/9 and visited the world 2/9 - 2/16. Here's what we did. We booked about 2 months prior to the visit. We hadn't bought our AP's yet but that doesn't matter because you don't have to have them in hand while booking. The official rule says you need an activated pass at check-in. So, we opted to purchase our passes at Downtown Disney because those are already activated. When we went to check in, they didn't even ask to see our passes. But, just to be safe I would have them before your check in. No need to buy them now or stress at all. It's easy.
They usually offer AP discounts about 2-3 months ahead. But that changes all the time. Check these boards and mousesavers.com. I think they do offer discounts for your time frame EXCEPT for Thanksgiving and that weekend. However, I believe the way discounts work as far as AP discounts is it's valid for check-in dates. For instance, we checked in 2/9 with an AP discount at the Poly of $179. On 2/12 that rate expired and went up considerable. But, since our checkin date was 2/9 we got that rate the entire time.
PamNC