The "Dispute" about the First Appearance of Hawkman

We've celebrated Hawkman Day together since 2016, and it's grown quite a bit. It's been recognized on many sites, and even got a mention in Jennifer DeRoss' fantastic Gardner Fox biography. But is November 10th accurate?

Hawkman first appeared in Flash Comics No. 1. The cover date is Jan. 1940. It has been the general practice since the 1930s for comics to put the cover date as two months after the actual release date. DC went to three months for a few years before going back to two.

So Flash Comics came out in November 1939. When I did some research back in 2016, I found two sites that listed release dates. The first was Mike's Amazing World of Comics. On this site, the date is listed as November 10.

The second site is the Grand Comics Database. This site lists November 20th as the release date. However, they also acknowledge the house ads' date of November 10.
They add this note: "The on-sale date of November 20, 1939 is the publication date reported in filings with the U. S. Copyright Office. However, a house ad in Action Comics #19 states the issue was to be on sale on November 10."
However, the November 20th date wasn't filed in the U.S. Copyright office until 1967. Which has led to the debate about the actual date. So I went to two other sources; The Hawkman Companion by Doug Zawisza and New York Times journalist George Gene Gustines.

Zawisza lists November 20th on pg 12 in Hawkman Companion. This book is an amazing collection of Hawkman history and facts. If you have never picked this up, I recommend it 100%! Gustines has also mentioned November 20th as the release date. Two very solid sources!
So which date is accurate? To be honest, I'm leaning towards November 20th, but there is debate about the actual date. What do you think? Let me know in the comments below!