Now, if i had dont this for DC/WB i have sort of an idea how i'd do it.
Start with WW for several reasons. She can be the oldest super hero, and the current trends suggest (and also prove) that people want a female super hero film series. Her movie would have taken place in the distant past and had her fighting aries but stayed in antiquity.
Next i would have made Superman, and it would have been set in the 1930s. Sperman's ship were recovered by the government but not him. He grows up on the farm raised by the kents and all that. Then great technological advances happen, aided by the reverse engineering of his space pod. This causes problems that Clark feels a responsibility to fix and does so as superman. Basically a recreation of the Fleischer cartoons and also at that power level.
next movie is a sequel to superman, where he goes to fight in WWII, there he meets Wonder Woman and also Jay Garrick Flash. Together they fight the fictional country of Markovia which has acquired advanced military weapons, once again because of the space pod stolen from superman. The three heroes assist the allies and stop the Markovian war machine. Doing this allows the allies to concentrate on the other theaters of war and WWII plays out as normal for them. WW hears about the atom bomb and begins to agree with her mother about mankinds evil and returns to Themyscira
Next movie would be superman fighting doomsday. Wonder Woman would return to help superman as he is dieing attempting to stop doomsday. We also get the flash and possibly some other heroes appearing, trying to help superman but Doomsday is just too much. In the end Superman defeats doomsday and dies. This would be in the 1960s. The movie ends sadly but on a bitter sweet note as Dianna forms the JSA to protect the world in the absence of superman.
the batman movie would start in the 80s.