A mechanics stethoscope also works really well in detecting early bearing failures. Jack the wheel up & push the brake pads back with a putty knife. Then place the stethoscopes steel probe right on the spacer collars. Rotate the wheel by hand. You can't miss the sound of a bad bearing...
Your trying to catch Early bearing failure,,, Forget waiting for play or wobble, if they have play or wobble they have been bad for a long time.