Not a GFN user myself, but doesn’t GFN simply use the steam backend? (At least for games that only are supported via steam).
So I would heavily assume it will be available once the patch will be avaialble for download right at release time. It might take a few mintues until the GFN backend has patched the game as well.
So if you are having a low bandwidth to downlaod the LE update yourself I guess you can expect it within a few minutes of the patch releasing.