Sounds like it was written very late on the 6th or early/wee hours on the 7th; 13 days added to that puts it very late on the 19th or very early on the 20th.
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I have it dated 12/20/20
ThankQ!
I figured back from Jan 20th 13 days, and the —latest— it could have been written would be late Jan 6/early Jan 7th.
Good find on that 12/20 version; that it has stuff added between then and now makes it.... interesting shall we say.