OK, I got stuck again. Been stuck on day 8 for over a week, I think I need a hint. My current thoughts are below.
Spoiler!
The M is missing in December, so my initial thoughts were 1888 in roman numerals, but i tried both MDCCCLXXXVIII and DCCCLXXXVIII and neither worked. I also tried 2888 in numbers and roman numerals too, just in case. Also the second 8 looks different then the other 2, but not sure if I'm just grasping at straws. And i went down the rabbit hole of events on specific dates. But am I on the right track with roman numerals?