Almost...the zipper application looks to me that it was done simultaneously. To me it looks like the bias was sewn at the wrong side of the fabric but was not completed on the front. Then the zipper was put it and then the bias was wrapped around and sewn over the top of the stitches to give a seamless look. Just my two cents...and honestly, that's how I'd do it.
Creating cosplay heaven in my own private hell, one costume at a time.