Mark Hughes over at Forbes, had a chance to talk with Batman vs. Superman director Zack Snyder. It's an extensive interview we recommend you read. One of the things Zack reveals, is when Batman became part of the equation in the Man of Steel sequel.
He goes on to talk about how cool it's been to see the Batman, Superman, and Wonder Woman costumes together, but didn't give up much on when the official photos will be released:
Unfortunately, I don’t even know the timeline… Because the movie takes place so far from now, it’s hard to know exactly. That all gets tied to marketing and strategies for the movie. It’s not just a free-for-all, which I’d love it to be.
Then again he added this, after being asked about leaked set pics:
The one nice thing is that, the schedule is designed carefully so that I don’t know that that’ll be [a problem]– but who knows, these cats are pretty good at getting the drop on us with these photos. But, when we finally do show it, it’s gonna be real fun.
So what we think he's really saying, is that they're releasing the costume stills before they start filming anywhere where the paparazzi could scoop them out, aka on location.
Zack also mentions his surprise, after finding out how attached people are to the film version of Superman. Again, you'll want to read the whole article. Stay tuned for updates from Detroit!