You need to set the first Rotation (or any other parameter) at the point you want the animation of that parameter to start. Example, object flies onto screen, stops, at THIS frame you must make your first Rotation keyframe. Then move the playhead to the desired fame the rotation stops, then set the rotation paramters for how ever many rotations you want it to do.
What you are doing is setting the last keyframe, and Motion by default uses the start of the clip for the first keyframe. There MUST be at least two keyframes. So set the first one manually where the rotation is to start.