Really, on the A320 series I thought it still shouted retard at you at about 30 feet. Otherwise, with the thrust levers in the normal flight position, (the climb detent on the throttle quadrant), when the weight comes on the wheels, the logic changes to ground mode from flight mode, and power is controlled by thrust lever angle, not autothrust. And you would get plenty.
During a manually flown landing the auto callout comes at 20ft.
During an autoland the callout comes at 10ft, and is a reminder for the pilot to close the thrust levers. However, the thrust will have automatically reduced to idle by this stage.
DH