I had wanted this to be some sort of in depth exercise in comics journalism but I kind of stalled when doing a small bit of research. So instead I'll just put out some unsupported conjecture.
A couple of weeks ago I wrote about DC's new publishing direction. I get frustrated when fans don't understand the long lead in times for deciding creative direction and producing a comic. When I read the Multiversity guidebook last weekend (it's really rather good) I came across a story with Earth 8 and Earth 42.
Earth 8's logo:
Earth 42's inhabitants, named the Little League:
In the last panel they've been taken over, they weren't always red eyed monsters.
Now, the Little League most likely were developed from the chibi Justice League from the pre New 52 Superman/Batman series:
But, to get to the point of when this stuff is developed, I think Morrison's Multiversity concept was developed in 2012 or 2013. i.e. about 2 years before it was first published. I think this because there is a webcomic, now called JL8, but which was originally called Little League.
I first came across and reviewed this webcomic for New readers... in 2012. I know this because that's when the review was published, and I didn't write reviews too far in advance back then. The review states that were about 40 strips published at that point. I remember seeing a post from the creator, Yale Stewart, saying that DC had contacted him telling him stop using the name Little League because, if my memory serves me right, his webcomic's use of the name was copyright infringement or some similar thing. Apparently it was a legal letter and I got the impression it was pretty official and scary looking. So he changed the name to JL8. I reflected the name change in my post, but sadly I didn't note the date of when this happened. That'll learn me.
So, go have a look through at the JL8 tumblr. Notice the chibi style of the characters.
Now to my recollection the chibi Justice League were never named the Little League in the Superman/Batman issues they appeared in, or in the Halloween or Christmas issues they had an appearance in (It was one or t'other).
So, my point is that if DC sent a letter to the creator of JL8 in 2012 or 2013 saying he couldn't use the Little League name, that could mean that they were thinking about and planning out Morrison's Multiversity as far back as then. The ideas could have been purely at concept stage, or they could be being drawn out and the Multiversity being created and nailed down.
(I wish I knew the date of the change, or could find the post that Yale Stewart, the creator put up announcing the name change).
Or it could mean that DC were looking to capitalise on the Chibi Justice League at some point but they weren't sure when or how. I think this idea is unlikely though, as the New 52 was launched in August 2011 so I think they'd be mostly busy with that and not with very conceptual ideas that might never see light. What would be the point? If they were annoyed with the JL8/Little League series existing they could have filed a proper take down notice to the creator. They didn't, they just said the name had to change,
Of course, this could just be wild conjecture from me, but I think it goes some way to demonstrate how far in advance DC plan their storytelling. It's for sure not just a few months in advance.
This all feels a bit self indulgent, sorry,