Shoulders and hips in line with the board. It has nothing to do with the amount of flexion.
I see. "A little open" therefore means pointed forward a bit, correct? That's how I learned, then gradually migrated to stacked.
I set up my daughter's bindings duck in hopes that she becomes comfortable riding switch right from the start, but do you think it's better to ride a little open until she gets things down a bit, then worry about learning to go switch later?