Thanks for taking some interest. I’ve spoken to my wife, who used to sew a lot, about this and we talked it over. Our sense was, finally, that if the interfacing were on the front-facing piece, the pocket flap would never wrinkle to match any wrinkly looking fabric adjacent to it. I often don’t iron my shirts, and we agreed that it’d look odd to have two nice flat pocket flaps there on a shirt front that was a little bit wrinkly. So, … I put them on the part of the flap that’s going to be on the back of the flap. Today I practiced button holes. We go slowly while we’re learning new stuff. Thanks again.