I make my binding and pin it in place on the quilt, not pinning it closely. This method achieves 3 goals. I can make sure it is long enough, and a binding seam doesn't land on a corner. If it does, I move the starting point a couple of inches. And also, I do this so the binding isn't all over the place and twisted as I sew. I remove pins as I sew and let the binding sew in place. This works great for me and I don't have to deal with the loose binding as I sew.