I feel it could be the end of Season episode as a big finish, I don't see it happening at the beginning or middle, because then I don't think the Season finale would be as big a moment or special by comparison.
Of course who knows, but my bet is it's gonna be a Season finale thing.. It just being another episode in whatever number season, would seem kinda lackluster, so I feel it's a Season finale thing.
Now what Season final who knows. Although considering the next Season is gonna be an ESB of sorts, where very bad things happened to the main cast....yeah..