Info on the 1st big issue buttons is arguable at best. UMA has an entire 18 pages and counting devoted soley to the Elwar 1st button issue mystery. (elwar button mystery).
Ill break it down best I can. The 1st issue Big Buttons can be seen in a photograph of Forest J. Ackerman at a store promoting the Famous Monsters paperback release sometime in the early 1960's.
He is clearly wearing the 1st issues, because the artwork is less refined than the 2nd issues released.
it comes down to early 1960's release for the 1st Big Buttons. and I believe the little buttons offered in gum ball machines came later, because the artwork is the same on the little buttons as the 1st issue.
Theories abound about why the big 2nd issue buttons were produced.
from Universal copywright infringement on their monsters, which makes more sense to me, to the original artwork lost to a fire. Anyways, the 1st issues are extremely rare, and when they pop up for sale, dissapear quickly.