When Does "Batman: The Return of Bruce Wayne" #1 (2010) Take Place?

"Batman: The Return of Bruce Wayne" #1 Part One "Shadow on Stone" is a science fiction superhero comic-book written by Grant Morrison that released May 12th, 2010. So when is "Batman: The Return of Bruce Wayne" #1 set? 

It takes place on the fictional DC Comics Universe timeline roughly in the year: 

~312950 BC 

We know this because Bruce Wayne/Batman interacts with Vandar Adg/Vandal Savage and other Homo neanderthalensis (neanderthals), a real-world different species of human that existed between 241000 BC and 38000 BC. In "JSA: Classified" #10 (2006), which takes place around the year 2000 AD, Vandal Savage’s internal monologue textbox declares, "I have lived for 37,000 seasons..." so it is most likely after 35000 BC. 

2000 - 37000 = -35000. 

(All this is possible for Batman to witness because he has been hit by the Omega Sanction in a scene shown both in "Batman" #702 [2010] and "Final Crisis" #6 [2009].) 

More specifically, midway through the comic Vandar Adg refers to himself as "The chief who scares death" so its likely he has already gained immortality, an event depicted many times in flashback. Although it is not in the same universe and the years do not line-up, the Vandal Savage of The Golden Age/Earth-Two says he became immortal when "In the year 1,000,000 B.C., I was a man forty summers old…. chieftain of a tribe of cro-magnon men"… in his first appearance in “Green Lantern” #10 v1 (1943). So it is likely after 34960 BC. 

-35000 + 40 = -34960. 

In yet another alternative, in “Batman” #903 (2023?), the current version of the character says, “I am Vandal Savage. I am fifty thousand years old..I am immortal.”, then, “It wasn’t always the case.”, and finally, “In my youth, the skies lit up as meteors showered down…” So it would likely be after 499?? BC . 

-50000 + 40 = -499??. 

Boy/Robin's line makes clear that the Miagani -- the traditional Bat Tribe that lived around Gotham, introduced in Jim Starlin and Bernie Wrightson's "Batman: The Cult" -- were an evolution of the Deer Tribe inspired by Bruce's presence.??? 

(HOWEVER, Grant Morrison said in an interview that "The first episode is set in the Late-Paleolithic Era". This is now referred to as the Upper Paleolithic Era and that would place it some time between 48000 BC and 10000 BC. This is, of course, epitext and therefore not conclusive.) 

It has been retroactively collected into a complete paperback and a complete hardcover. 

It is a chronologically early comic in the DC Comics Universe multiverse timeline (a final chronological story to feature Anthro, the first boy) and can be read at its timeline point or after "Batman" #702 (2010) in a Batman read-through or after "Final Crisis" #7 (2009) in a DC Universe read-through.