home run swing (1898)

“Uncle Dick Buckley was at the rubber smarting over a strikeout, on his other time up, and it was plainly evident that he had his home run swing with him, as he turned a couple fouls over toward the wagon gate which gave his intentions away.” “Three Straight: Records of the First Series with Milwaukee,” Columbus Dispatch, April 25, 1898, p11

No earliest use given in 2009 Dickson Baseball Dictionary