It's still unknown, really. It's just down to experimenting and seeing what makes the most practical sense.
There was definitely animal glue found during the scientific analysis of the arrows, which is most likely hide glue for gluing the fletchings down first, but it's impossible to say where in the many layers it occurred.
When you go and look at the MR arrows in person, you can see that on some the thread is still there, some have the impression marks and thick glassy compound, on others it's just an impression with no adhesive left at all, and on a few there's absolutely no sign whatsoever of anything at the fletching end - no glue, no compound, no binding marks and no feather impression.
My personal view having tried many methods and from studying the originals is that it was done the way I made these, but I know others will swear by a different method!