For me, it's Thursday.
Even still, today is widely regarded to be an important day in America, frequently used by American Christians as a jumping block for evangelism. If only there was some way of marking the occasion, even though in Scotland the occasion means nothing and as such Thanksgiving tracts are not used.
WHY LOOK AT THIS
I owe my own thanks to my parents for this one, They recently came back from a trip to New York, and they brought back some souvenirs from a tract stand they came across. They also brought back some Hot Tamales and some Cookie Dough bites. Hot Tamales are awesome. Cookie Dough bites, not so much. Take note America. Chocolatey things are NOT your forte.
as early as 1565 amongst the Spanish settlers in what is now Florida, albiet in much more modest forms. The big turkey feast in 1621 Massachusetts was just when it became more or less solid tradition.
THANKSGIVING BONUS: I don't cover tracts that I don't have a physical copy of, but for the enthusiasts out there, Jack Chick's "The Missing Day" is MORE than worth a look. If you want to see it being torn apart, I'll just direct you over to J Crowley's review on Enter The Jabberwock. He does a much better job on it than I ever could.