Updated.
The order for the current seasons is, as always, subject to change. Sometimes there will be very large changes as new information becomes available so make sure to check back often if you're actively using the guide.
I also changed the color coding.
I'm assuming Black Lightning will be on its own Earth at this point with a crossover down the line, much like Supergirl (Earth-38) and Freedom Fighters: the Ray (Earth-X)
I am also always on the lookout for help, so if you happen to notice any inconsistencies please point them out.
I will still try to get back through the earlier seasons to fine tune the order but no promises on a timeframe.