“The grand stand was reserved for ladies, a very numerous assemblage of whom were present.” Philadelphia Sunday Mercury, September 6, 1868 [Richard Hershberger]
Previous earliest use (Dickson Baseball Dictionary, 3rd edition, 2009):
1ST USE. (Definition #1) 1870. “The immense audience disposed for the most part, on the seats of the ‘grand stand’” (Lakeside Monthly, 4; David Shulman).