Some people do use Aulani as SAP, but if you're planning a WDW trip with them, you have nothing at WDW until the 7 month mark. There may or may not be availability.
It's generally best for SAP to be at WDW in case you are unable to move from your home resort. It's also helpful for them to be a resort with lower point costs per night than other resorts you may want to move to, because then you're adding point usage at the 7-month mark instead of having points that you may have already banked or borrowed get stranded.