Given how BvS ends, this is how JL should begin.
"THE DAY SUPERMAN RETURNED": Darkseid is already waging war on humanity. When it seems like all hope is lost, Superman returns in spectacular fashion.
He gets introduced to the other members of the team, and then we flash back to how this crisis started. We discover that the team NEEDS Superman to lead them, and then we jump back to the present as the united JL takes the fight to Darkseid.
This would continue the theme of each movie beginning with an apocalyptic battle.
"THE DAY SUPERMAN RETURNED": Darkseid is already waging war on humanity. When it seems like all hope is lost, Superman returns in spectacular fashion.
He gets introduced to the other members of the team, and then we flash back to how this crisis started. We discover that the team NEEDS Superman to lead them, and then we jump back to the present as the united JL takes the fight to Darkseid.
This would continue the theme of each movie beginning with an apocalyptic battle.