Well, I got a Thursday departure, but Expertflyer didn't notify me about Friday availablility and when I checked it was already gone. So it seems that for some flights it does it right at the 330 day mark, for others, not.
It seems like you need to query EF pretty regularly at the 330 day mark. I'll probably be happy with the extra day off when it comes, but I would really have liked the Friday. Perhaps thats just too greedy.
Now I have to hope for a Sunday return.