Board Thread:Comics/@comment-24680401-20141224222445/@comment-1038387-20141224222818

The cover date is March/April. It's not a publishing date, it's sort of an expiration date. The cover date is 2-3 months after publication. It's so the news agent knew when to remove the old comics from the racks.

I'm unsure what the exact difference was in the Golden Age.