It looks like Toscanini/NBC Symphony was first. Four months ahead of Bruno Walter/ New York Philharmonic.
They finished their set on November 19, 1952 with Symphony 8.
All nine Symphonies were on LP by early 1953.
I don't know when the boxed set was issued. Anybody?
Bruno Walter/New York Philharmonic finished their set on March 7, 1953 with a remake of the Symphony 9 finale.
All nine Symphonies were on LP by late 1953.
I'm pretty sure it was not issued as a boxed set until much later - late 1960s on the budget label Odyssey.