New rotors always go on with new pads for me. Modern rotors are made lighter than they were years ago. True, they have a minimum thickness spec, and usually the guy cutting the rotor will most likely always unnecessarily cut to minimum thickness whether they need to or not.turning the rotors is never a permanent fix... they become thinner and become easier to warp again... what does prevent rotor warpage to begin with is to make sure the lug nuts are evenly tightened... a torque wrench achieves this... go to a mickey mouse shop, and they'll blast the lug nuts on, "like a race car"