The right side (as worn) seam is similar to the previous step, but with a gap between the notches (for the strap to pass through when the dress is worn.) At bottom edge. stitch up to notch, backstitch then leave gap between notches unsewn for 2.5cm(1"). Backstitch where you resume stitching and continue to end of sleeve.
Press seam open. Stitch a rectangle shape around the gap at 6mm(1/4").