This is a really interesting and fun timeline, and I especially love it from a writing standpoint alone. I really like how it's assumed that the watchers of the channel (and, out-of-universe, we the readers) are already familiar with this history, and the events and people mentioned in it...
May Day was a total stab in the dark, and it's a stretch to call the Lunar Landing Anniversary a holiday, so I'm not surprised I got those wrong. Great hints for the episodes, though, looking forward to reading more!
Assuming that they're in calendar order...
The Time Ravagers (New Year’s Day)
Save the King (President's Day)
SLEEPY (Valentine’s Day)
Where the Weeds Grow (Arbor Day or Earth Day)
Mister Milk (May Day/International Workers' Day)
Lift Every Voice and Sing (Juneteenth)
From Cradle to Early Grave...