It all depends on what is comfortable to you...honestly.
I used to ride all the way out and ducked to 15 on both feet. My knees started killing, so I moved in 2 holes (to about a 20.5 inch stance width) and straightened out my angles and now my knees don't bother me. Just try out a few different stances and go with what feels best!
Oh Hi Kim! Just realized it was you