The AP should be bought when you get to WDW - then it will be good for a year from that date. The day it is activated, it is good for a year from that date.
If you purchase it now, you will lose several months, if you are not going to WDW before December
The AP should be bought when you get to WDW - then it will be good for a year from that date. The day it is activated, it is good for a year from that date.
If you purchase it now, you will lose several months, if you are not going to WDW before December
Unless it's a renewal you won't get an activated AP if you purchase now, it will be a voucher that you activate when you get to WDW. I would only bother buying in advance if you are trying to get all your expenses prepaid before arrival. Otherwise it's just as convenient to buy at the parks.