Depends on the school and how they audit your training study period.
If you say have a Mech Eng Degree the tech subjects are a farce a part from lowering your knowledge base down to french standards.
So you could get by, by fibbing about the study time until 4 weeks.
2 week brush up which will teach you all you need to pass.
Non tech subjects are a bit of a bitch more about learning !!!!e than anything else. Again 4 weeks full time plenty of feedback and no worrys.
It dosn't work foreveryone though. The Mech eng reference means you have already learned AC DC electrics for the 4th time in your life etc. And you will be able to try and work out the question from first priciples if you don't have a clue.
You can't go to the brush up cources without reading the books but I can garantee that you won't spend as much time on the second set as you will on the first if you pass the first time.
Min time including exams would be 4 months if I had to do them again.
MJ