Twice through a hot wash cold rinse was enough to felt the bag. It's quite a bit smaller than I imagined but just about bang on the pattern dimensions. Right now it's being blocked around a box to give it a nice stiff shape and a flat bottom so it will sit up on its own. I'll leave it that way for a day or two before finishing it off with the straps.
Meanwhile, I've decided I am going to finish the Florence scarf and a chenille scarf and possibly finish an old (boring) cardigan that have been incomplete for so long.