Welcome to Earth-304d!
When writing for DC, I've always taken the Arrowverse as my template for the universe, but over the years my personal alterations for it have been piling up. Now that I'm reading the comics, I came to the conclusion that instead of altering elements of the Arrowverse, I could as well create my own Earth in this multiverse and cherrypick canons from the comics and their various adaptations, give them my own spin and make it my Earth. Which also means; no specific background knowledge of any one comic run or adaptation is needed, all elements that will be important for the stories are going to be put into the stories.
This is going to be a collection of oneshots all set on that Earth. I want the stories to work as standalone oneshots, so you can just pick which heroes' tales actually interest you and ignore others, while I also do want the stories to tie together through referrences, cameos and crossovers (i.e. Justice League) in a manner that's supposed to work without requiring full knowledge of what the other heroes have going on individually, so you can focus on reading, say, all the Aquaman-featuring stories and ignore Batman's standalones without being lost.
I want to tell the stories of my favorite heroes and how they came to be and what alliances and teams they join on this altered Earth. There will be some romances, but the main focus is on the found family team feels of it. At the heart of this universe are Superman, Wonder Woman, Batman, Aquaman, Flash, Green Arrow, Batwoman, Supergirl, and the Birds of Prey.
Timeline (for orientation; will be updated as the world expands):
1983: Thomas/Martha Wayne die
1984: Kal-El lands on Earth
1994: Bruce Wayne becomes Batman (in Batman: Gotham Grief)
2002: Jefferson Pierce becomes Black Lightning
2003: Kara Zor-El lands on Earth
2004: Clark Kent becomes Superman (in Superman: First Flight)
2004: Dick Grayson becomes Robin (in Batman: Gotham Grief)
2005: Diana and Arthur Curry become Wonder Woman and Aquaman (in Wonder Woman & Aquaman: Of Two Worlds)
2007: Oliver Queen shipqurecks and is pressumed dead (in Green Arrow: You Have Saved This City)
2008: the Justice League first forms around Batman, Superman, Wonder Woman, Aquaman, Zatanna, Black Lightning, Martian Manhunter (in Justice League: Dawn of New Gods)
2008: Barry Allen becomes The Flash (in The Flashes & the Rogues: Cold as Frost)
2009: the Teen Titans form around Robin, Miss Martian, Aqualad, Superboy, Wonder Girl, Cyborg, Supergirl (in Teen Titans: Clones and Sidekicks)