P.savage,
There is a 3-year time limit between passing your last exam and getting your CPL/IR. There is (I think) an 18-month time limit between passing your first exam and passing your last exam. So, from that point of view, you don't want to start the exams too early. Apart from which, as Capt BK said, you need a PPL before your exams.
I think it makes sense to leave at least some of the hour building until after the exams. Otherwise you'll be going into the CPL training very out of practice, and it will take longer to get the CPL than it would otherwise. I note that the course structure you've given does include some hour building between the exams and the CPL, but you don't say how many hours are included in this particular chunk of hour-building.
Capt BK - I would disagree with you regarding getting the IMC as part of your hour-building. You have to fly for around a hundred hours, you may as well do something useful with that time. The IMC has several benefits - not least of which is that it has to make the IR at least a little bit easier. When the alternative is to fly around aimlessly, I'd definitely opt for the IMC.
FFF
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