Black Lightning would like to discuss his costume

Not a bad rationale, really. Not bad at all. Of course, it only really works if the DCU was set in real time, and Jeff got his start in 1977.

The problem is that it's now 2007, so Black Lightning has either been an active superhero for 30 years—making him around 54 years old or so, and making Superman, Batman and all of the other characters to debut before him even older—or else he simply debuted later than that.

See, the DCU used to be set on a sort of sliding timeline, formalized in great detail during the Zero Hour series (which even included a year by year timeline). Rather than assigning events in the DCU dates, which would anchor them to particular years, the Zero Hour timeline established a length of time ago that they occurred. So Batman didn't start fighting crime in 1939 or 1989, but rather "ten years ago." (This is also why his 1987 origin story was called "Batman: Year One" rather than "Batman: 1977")

Zero Hour posited a ten-year-old DCU, beginning around the Silver Age. Some things that would artificially mark the passage of time, like the number of Halloweens Batman experienced during his first year on the job, or how many Christmases Lois and Clark have celebrated since marriage, we all have to kind of agree to ignore as not really counting. Big changes, however—the birth of Lian and Cerdian, Tim Drake becoming Robin, etc.—will inevitably artifically move the timeline forward.

Since Zero Hour occurred in 1994, everything that happened in the DCU between then and Infinite Crisis obviously can't fit into a single year, but we still want to err on the side of too little time passing instead of too much.

So, at the least, when Infinite Crisis occurred, eleven years had passed since Superman started superhero-ing (at the most, maybe 13 years).

Then came the "One Year Later" jump, which added an entire year onto the timeline. So now, if this week's comics are set as soon as, like, two weeks after 52 #52, we're still looking at a DCU that's at least 12 years old.

(Of course, in the months before Infinite Crisis, and then during that missing year, the entire history of time in the DCU was damaged repeatedly by Superboy punches, Alexander Luthor's rejiggering of the DCU into a "New Earth" and then Mr. Mind's random alterations to the new, 52-world multiverse. So anything on the Zero Hour timeline could be changed—maybe Superman debuted 20 years ago, or five years ago—but there hasn't been any kind of formal declaration. We know a few things that are different, like Wonder Woman appearing in the U.S. ten years before Zero Hour instead of four years before Zero Hour, but for the most part we know what hasn't changed, not what has. And nothing that pertains to Black Lighting. So Jeff and I are going to have to work with the most recent info available, which was provided right after Zero Hour).