I know a few wore white as early as the 1930s. But ND didn't first wear white until 1955, I believe. Oddly enough, that was for a home game, the opener against SMU. I think it's the only time ND ever has worn white at ND Stadium.
Green used to be ND's counterpart to white. ND wore green on the road as late as 1962 (look for photos at linked ChiTrib archive story) at USC and 1963 at Purdue (see below clip).