I did more or less all my studying on the train into work.
You will learn a lot in the brush-up phases. Not just facts but tricks to remember information too.
It took me months to feel ready for my first set of exams. It involved learning the theory, hitting the QB and doing the brush-up. Once the exams were booked it was just a case of hitting the QB right up to walking into the exam room. I don't remember seeing any questions I hadn't answered before.
After that my second and third set I did in around 2 months each. It is easier once you know how to play the game.