Just because you HEARD about the Marvel Sony deal at a certain time and then a deal was done quickly does not necessarily mean the deal wasnt in the works for a much longer time than that,
Nah, it probably only took minutes...
"Hi, Sony, This is Marvel. You remember that Avengers movie?"
"Yeah"
"It made more money than everything you released last year combined."
"Yeah."
"And the Thor movies"
"Yeah"
"And the Captain America movies"
"Yeah"
"And the Iron Man movies"
"Yeah"
"Can we use Spider Man in the next movie? We'll give you a percentage."
"Yes, please do. Use him in every movie. We'll send a catalog, pick any Sony-owned character you want. Use them all. Please. Please!"