home plate (1866)

“Wilkins took the bat, but through a series of passed balls and overthrows Reach was enabled to make the home plate.” and “Sensendorfer sent Dockney and Fisler sent Sensendorfor home and, amid tumultuous applause, reached the home plate also.”The National Game: Champions Match at Philadelphia Between the Atlantics and Athletics,” New York Herald, October 23, 1866, p10

Previous earliest use (Dickson Baseball Dictionary, 3rd edition, 2009):
1867.  (New York Herald, Sept. 26; Edward J. Nichols)