On-sale date is publication date in Catalog of Copyright Entries Periodicals 1945, page 505.
First Avon comic book.
This is probably a reprint from an earlier Chesler shop-supplied comic book.
The first panel has been revised: a dialogue balloon reading "I'm a Penner fer keeps, now!" has been erased. Possibly Joe Penner's permission wasn't obtained for the reprint, or the editors thought people had forgotten who Joe Penner was by this time. The subsequent reprints are the revised version.