PROLOGUE:
In the course of writing, I found myself needing to figure out if one of my stories came before or after another one, as I like to keep my stories "in continuity" with each other. It occurred to me that not only would a handy timeline help me, but it might also be beneficial to my readers as well, since the release order of my stories means nothing, chronologically speaking, yet occasionally they might refer to one another. So, with that said, here's the timeline. All the dates are guesswork or outright made-up by me, and subject to change if/when I notice a mistake or if I want to make it conform better to canon. That said, the show plays very fast and loose with continuity (Dash's comment about Tank's first winter, despite already having a Christmas episode) and I've never been a stickler for it anyway, so I'm not going to worry too much about it.
Call it a loose canon, if you will.
THE TIMELINE:
Epochs are measured in "Before Nightmare Moon" (B.N.) or "After Nightmare Moon" (A.N.).
40BN:
Special Illumination (unfinished)
Untitled Starswirl Adventure, concerning an adventure to Neighbakhr (not started)
25BN:
Hearth's Warming Eve, play contents
0AN:
Princess Twilight Sparkle, duel between Celestia and Luna
The Mare in the High Castle, universes diverge
1000AN:
SUMMER SUN CELEBRATION
The Mare in the Moon, season one starts
Swarm of the Century
WINTER
1003AN:
WINTER
The Crystal Empire, season three starts
Pinker, Paler, Scolder, Pie (unfinished)
Trip the Light Fantastic
Magical Mystery Cure, season three ends
SUMMER SUN CELEBRATION
Princess Twilight Sparkle, season four starts
Rainbow's End (in progress)
Castle-Mania
WINTER
1004AN:
WINTER
Inspiration Manifestation
Josh goes to equestria (intentionally outside continuity)
Equestria Games
No Pony Left Behind
Twilight's Kingdom, season four ends
The Cutie Map, season five starts
Tanks for the Memories
WINTER
1005AN:
WINTER
SUMMER SUN CELEBRATION
The Mare in the High Castle, alternate timeline[1]
Rarity Investigates
Shallow Diamonds (in progress)
Made In Manehattan/Brotherhooves Social
Twi-Write Here, Write Now
Crusaders of the Lost Mark
Rainbow Dash's Super-Awesome Self-Insert Figures Out If It Would Matter
Equestrian Time-Slip, alternate timeline
Hearthbreakers
WINTER
1006AN:
WINTER
The Cutie Remark, season five ends
No Pony Left Behind 2 (intentionally outside continuity)
Do Hippoids Dream of Electric Shetlands?, alternate timeline (not started)
SUMMER SUN CELEBRATION
1012AN:
Flow My Tears, the Fashionista Said
[1]: Due to the frozen celestial mechanics, time in alt-Equestria is largely guesswork. The events of High Castle take place in what they think is (the Equestrian equivalent of) February, 999AN.
Where are you now? You're interesting.
1998862
Quoth Rarity, "The beauty of Nightmare Night is that you don't have to dress up as something scary."
You... You put Angel's face on Angel Bunny's body?
community.us.playstation.com/t5/image/serverpage/image-id/168777i746055A35B1C099F/image-size/original?v=mpbl-1&px=-1
You're an actual monster.
1993002
That's for the courts to decide.
1992992
No. No.
YOU. YOU DO.