Unless policies have changed recently, you can book the AP discount for your room now even though you don't have your AP yet. You will need to upgrade to the AP and show the APs to the front dsk within 24 hours of checking in to maintain the discount. Call the front desk of your resort to confirm.
ETA: Sorry - I just read your post more carefully - It sounds like you are getting the AP on a trip in the next few weeks, and then returning in Novemeber on a second trip. If that's the case, you can totally book an AP rate for the November trip - you'll have the AP in hand when you check in! You might want to look into if you can get an AP rate for the first trip (assuming you are staying on site), and then upgrade your tix ASAP after you get there.