FWIW, on the A320, provided the speed was on (or above) the target IAS, and the VS and profile were good, I routinely closed the throttle levers between 50 ft and 30 ft. (IIRC, it's done at 50 ft for landing-performance certification.)
On the B707, I wouldn't dream of closing the thrust levers before the flare was nearly completed, unless the speed was high...