Some (but not all) of the "Frozen Fun" is sneak peek-ing for the general public this coming Saturday, 12/20 (Olaf's Snow Fest, the Anna and Elsa meet and greet and the sing-along in DCA; and the Storybook Land Canal Boat ride with the new Arendelle additions will be open by 12/20). All AP holders except Premium or Premier AP holders will be blocked out by that date.
The other things (Freeze the Night dance party and the Frozen-themed show at the Royal Theatre in Fantasyland) will be open as of 1/7, and the other AP block outs will have been lifted by that point.
So I guess what I am trying to say is that they could do an AP preview for the Frozen Fun opening on 1/7, since that will be the whole deal and not just some of the offerings -- but some of the wind will have been taken out of its sails by the general public sneak peek that is taking place starting on Saturday, 12/20 (and on through the rest of the month).
As far as I know, there have been no AP Frozen Fun preview invitations for anything pre-12/20, and it is already 12/17 now.
Usually, the Parks Blog will do a blog to announce AP previews, or you'd get an email. I know that some out of state folks get the invites too.