Instead of doing a bias binding around the neckline of my little gowns, I decided to try a facing. It was a lot easier for me and I'll keep doing this. I like it MUCH BETTER! Please forgive the photos. They aren't the best, but I hope you can get the idea.
Lay gown flat (sides are not sewn yet) with right side up.
Place the circle over the opening in the neckline.
With a fabric marker, draw a circle about 1/4" beyond the neckline cutout.
Sew along the marked circle.
Cut out the neckline in the fabric that you just sewed onto the dress.
Notch so that the facing will turn easily.