Embroider your monogram towards the bottom of a piece of scrap fabric. Fold your fabric down on top of your monogram, right sides together. Sew up the two sides of your pocket. Now turn it right sides out. There should be an opening on the bottom of your pocket square. Tuck the edges in. It will be closed when you sew the pocket to your pjs.
Place your pocket square where you would like on the garment. I did one as a chest pocket and one as a hip pocket on another nightgown.