The advice already given is correct. You do NOT need to have your AP activated. In fact, you don't even need to have an AP to get the rate. All you do is call and tell them that you're AP and that you'd like the rate.
***DISCLAIMER***
While not illegal (at least I don't think it is), this is unethical and I do not condone this practice; that is, if you do not plan on purchasing an AP.
I don't think that there is a way for CRO to check if you are in fact already an AP holder. Book your rooms as soon as AP rates come out. Just make sure to have your AP in hand (not the voucher) when you show up to check-in.
My experience has been this: out of the many times we've gone, they have only asked to see my AP once. If I was a dishonest person (which I'm not), I could have used it without purchasing an AP. While I have NEVER done this, nor would I ever do this, I wish that Disney would close this loophole by simply requiring that all AP reservations show their AP passes 100% of the time when checking in.