Ironically, to move the bones, extreme tight lacing is not needed (going to tight is indeed dangerous).
You're objective is not to reign in the waist (which should be done by exercise and dieting anyway) but make the transition from the torso to the waist smoother. If your wearing, a 38 inch band, a 22 inch waist looks pretty stupid (especially with thin hips). So, how much you can cinch to make it esthetically pleasing depends on your current torso.
In my case, if I need it at all (which I probably do not) it would take a minimum, since my waist is 26.5 inch already and my under bust measurement is around 30 inch.