I feel like we're talking in circles now. Lucas involvement was discussed in detail very early on.
Here's a five part discussion with George and Kathleen about the future:
Lucas: I've always said I wasn't going to do anymore and that's true I'm not going to do anymore. But that doesn't mean I'm unwilling to turn it over to Kathy to do more. I have story treatments of 7, 8 and 9 and a bunch of other movies.
And obviously we have hundreds of books and comics and everything you could possibly imagine. So, you know I sort of moved that treasure trove of stories and various things to Kathy and I have complete confidence that she's gonna take them and make great movies.
Kennedy: We are absolutely going to make Star Wars movies and we're in the midst of the really fun part of the process. Which is sitting down with a couple of writers and we're starting to discuss ideas and we're starting to talk about what those stories might be.
I wanted to make sure that I wasn't going to be entirely on my own because it's important that he at least continue to be a little guardian angel on my shoulder helping me do this.
...
Interviewer: And what do you see your role is as Creative Consultant? What does that mean?
Lucas: I just said that I would back her up and I would be there. Especially helping with the script and making sure the script sort of...there's a lot of blank spots in the story treatment that hopefully we can fill in.
In addition, here's a great article that goes in depth on how the deal came to be:
How Disney Bought Lucasfilm—and Its Plans for 'Star Wars'
At first Lucas wouldn’t even turn over his rough sketches of the next three Star Wars films. When Disney executives asked to see them, he assured them they would be great and said they should just trust him. “Ultimately you have to say, ‘Look, I know what I’m doing. Buying my stories is part of what the deal is.’ I’ve worked at this for 40 years, and I’ve been pretty successful,” Lucas says. “I mean, I could have said, ‘Fine, well, I’ll just sell the company to somebody else.’ ”
Once Lucas got assurances from Disney in writing about the broad outlines of the deal, he agreed to turn over the treatments—but insisted they could only be read by Iger, Horn, and Kevin Mayer, Disney’s executive vice president for corporate strategy. “We promised,” says Iger. “We had to sign an agreement.”
When Iger finally got a look at the treatments, he was elated. “We thought from a storytelling perspective they had a lot of potential,” he says.
Based on that article and another I can't recall at the moment, I would say that Lucas didn't write up his rough outlines for the ST until after that meeting in May of 2011. Which would have given him around 14 months before calling Iger in June of 2012.
As for the franchise as a whole, I think too much emphasis is placed on Disney. Everyone seems to forget that the torch was passed to Kathleen.
When it comes to the direction and focus of the Marvel movie franchise people don't bring up Disney, they bring up Kevin Feige. The same should go for Star Wars and Kathleen Kennedy.