HuffPo has a ratherlongstreamofconsciousness post about 420 here:
https://www.huffpost.com/entry/420-meaning-the-true-stor_n_543854#:~:text=The%20origin%20of%20the%20term%20420%2C%20celebrated%20around,of%20cannabis%20in%20a%20Point%20Reyes%2C%20California%20forest.
Parts of it I recall but it doesn’t \fully\ line up with my recollection.
Waldos? Yes.
4:20 after school? Yes.
From here (and mentioned in HuffPo), I recall that it was coordinated to normal “tea time” in Amsterdam; every day at 1620.
Sort of like the drunkard, “It’s 5:00 somewhere!”
Amsterdam, at one time, was a droogie mecca for it’s lax rules regarding recreational drugs.
Thanks. I’m surprised they haven’t tried to make it a negative to pin on DT.