>Everything between The Crisis on Infinite Earths (1986) and Flashpoint (2011) happens.
This is fucked up because it includes so many major events, such as...
>Batgirl (Barbara Gordon) is shot and crippled)
>The Justice League of America breaks up and is soon replaced with the Justice League International.
>Robin (Jason Todd) is killed
>Batman gets a third Robin (Tim Drake)
>Superman dies and then comes back to life (whole story is like a year and a half of comics, but takes place in only two weeks).
>An evil Superman who tried to take the real Superman's place when he was dead destroys Green Lantern's home of Coast City, making Green Lantern go crazy and try to destroy the timestream and rewrite it as he sees fit. This is called Zero Hour: A Crisis in Time.
>A new Green Lantern (Kyle Rayner) showed up.
>The original Justice League of America reforms. Barry Allen and Kyle Rayner replace Barry Allen (dead) and Hal Jordan (evil). An angel named Zauriel replaces Hawkman (continuity so fucked DC said just to not use him).
>Hal Jordan sacrifices himself to save the world from the Sun Eater.
>The Spectre goes crazy after his previous host, Jim Corrigan, is allowed to go to heaven, so Hal Jordan bonds with him and becomes the new Spectre.
>Gotham is completely destroyed by an earthquake. The US government gives up and abandons it. Lex Luthor rebuilds it.
>Luthor is elected president.
>Our Worlds At War. Imperiex comes to destroy reality. It's portrayed as the biggest war since The Crisis on Infinite Earths. And I'm skipping Armageddon and many invasions by Darkseid.
>Identity Crisis happens. Jean Loring kills Sue Dibny. Batman learns Zatanna messed with his mind, starts building evil spy satellites.
>President Luthor is impeached.
>Blue Beetle dies.
>Hal Jordan comes back to life and becomes a Green Lantern again.
>Infinite Crisis happens. Everyone remembers the old history that was changed by the Crisis on Infinite Earths. They still remember the new history. Now they remember both.
>"52." A whole year passes. Superman, Batman, and Wonder Woman take a year off.
>Sinestro Corps War happens. Green Lantern's nemesis, Sinestro, makes an army of evil Green Lanterns and invades Earth.
>Final Crisis. Darkseid finally gets the Anti-Life Equation and takes over the world, almost destroying the universe. Actually he's just one small part of a villain called Mandrakk who almost destroys all of existence, including real life. Oh yeah, Batman dies here.
>Nightwing becomes the new Batman. Damian Wayne becomes the new Robin. Tim Drake becomes Red Robin.
>Blackest Night: Every character who ever died, including those who already came back to life, becomes a zombie.
>Turns out Batman wasn't really dead, he just got shot back in time. He gets back somewhere around here.
>Brightest Day: Follow up to Blackest Night where a bunch of characters come back to life.
>About a year and a half ago: Flashpoint
After Flashpoint, they established that in this new history, Superman first appeared five years before Flashpoint, and the Justice League appeared like six months after Superman. This is completely fucked, because so many major events happened in this timeframe and are still canon.
>Everything between Flashpoint (2011) and Superman: Reborn (2017) happens. This includes...
>Brainiac taking over the world at least twice.
>The Crime Syndicate of Earth 3 invades and takes over the world for a while.
>Pre-Flashpoint Brainiac threatens the entire multiverse with a tournament between every continuity ever because he saw the video game, Injustice 2 and hated it so much he threw a hissy fit about alternate universes and decided there could be only one.
>Darkseid fights The Anti-Monitor over The Anti-Life Equation. They both die (don't worry, they get better) and the Justice League (which includes Lex Luthor at the moment) all become the Gods of the Fifth World, but it doesn't last long.
>Superman Reborn
This story changes history so that Superman first appeared about 15 years ago. That gives much more time for events to have happened, and is the basic guide I'm using here. Also, I remember some stories immediately after Superman: Reborn, like Supergirl, mentioning that events that happened just after Flashpoint, like Supergirl arriving on Earth, were only about six months previous. So those six years between Flashpoint and Reborn were six months in universe.
>Everything since Superman: Reborn happens.
Actually I have no idea how much time has passed in universe since then, but I'm gonna assume it's about a year. Could be less.