Paul:
When I was doing the HOF rookies collection, the M101-1 (or National Copper Plate) Wagner was my choice too for representation in my personal collection. It certainly is a rookie and earlier than any other individual Wagner unless you want to go back in time and argue the Reccius card
. However, it's obviously a paper premium and not a card so does not qualifiy for rookie card status. Mine was in a BGS holder too, still doesn't make it a card because it was graded and encapsulated.
FWIW I believe that I was the first collector to have M101-1's, M101-2's, M101-7's and M113's graded and encapsulated by Beckett (they were the only TPG at the time to have a large enough holder to do it) back in the late 2000's. All are paper premiums and not cards, being graded does not change that.