You are correct, but the timetable the big12 has set is that they would like 12 teams by the time we start the conference title game.
I don't think the BIG12 will rush the decsion because they can hold a 2017 championship game based on a 10 team conference. The latest I have seen is a decision by early October and that might be early.
NO WAY does the Big12 add any teams unless their is a guarantee from ESPN and FOX that they will pay additional rights fees for the added teams. We all know if lawyers get involved, this process could easily slow down.