Do they just pick a date? Or are there some archaic rules governing earning report dates..
Updated from link provided by Bob Baerker.
The essential SEC requirements are that each public company file quarterly earnings reports on Form 10-Q or 10-QSB and yearly earnings reports on Form 10-K or 10-KSB.
A company can announce earnings publicly whenever it chooses, provided it follows the timing guidelines set by the SEC.
So they can pick whichever day they want within an SEC prescribed window...