Just an opinion from somoene who has been through the selection process this year. Anything can happen! (My course ranges from people who have waited almost three years to get a start date to someone who got -1 days notice - he was called on our first day!)
However, I find it hard to believe that you could go from the intial selection test to passing the interviews and getting a start date offered within less than a month of that intial test day. Especially if you believe everything your reading about the current selection process.
Are you in this position or are you just asking a "what if" question?