I hung my DTD on my dress form and stuffed it with polyester fiberfill.
The first time I stuffed it, I started from the bottom. I managed to over stuff it, and it exploded. It was easier to stuff it from the top down. The polyester fiberfill doesn’t easily slip out, so you can don’t have to worry about holding it up while you are stuffing it.
The above images are pictures of me.
I wrote a review of the process at PatternReview: Notion review for DTD