The crown is rather flat, as it's designed to be worn as sun protection and flat on your head. I beribboned it and during the first trip discovered a few flaws due to this shape.
Let dry over night and you'll get a nice, cone-shaped crown, still flexible enough to fit to your head. The bottom of the crown can remain round or you can flatten it once the actual size has been determined.
Put this on as you would the finished hat, if possible with updone hair so you discover where it sits perfectly. Sew a plain cotton ribbon around right where the brim starts to retain this size. If you like, you can flatten the back of the crown by moistening it again and pressing it flat. I just put it on the floor and put a bottle into the crown. Simple as that.
In the meantime, buy a properly shaped hat at a reenactment because you lose your patience and need sun protection...
I sewed the previous green hatband back on (invisible stitches), as well as the satin ribbons. All that's missing now are the proper pictures ;)