If you want to sew to the back first and bring around to the front to machine stitch, here is something I always do so I can hit the first line of stitching with the stitching on the front. Before you start sewing the binding to the back, fold your binding into thirds and make a nice crease. This will tell you exactly where to stitch so that when you fold over, it is all equal. If I use a 2-1/2" strip the seam allowance usually ends up being 3/8". Since I figured this out I sew all my bindings on by machine.