I've heard that air layering is more successful if done while the plant is actively growing, and like you mentioned, I think with this method it might be good if it's done after chances of frost or freeze have passed.
I can't speak from success unfortunately, just failure.
I did a few air layers about a year ago in late Fall and didn't have much luck. The
trees had pretty much stopped growing by then, so that was probably why they failed.
I might give it a shot later this Spring along with some regular air layers and see what happens.