Correct, it doesn't really matter when you fly the hours. Given a blank schedule it would probably be better to concentrate on the exams, then fly - simply because you'll have a lot more recent experience when it comes to talking the CPL and IR tests. Broadly speaking, the more hours you have in a short period of time immediately prior to your test, the more comfortable and proficient you would expect to be. But other factors come into play in the real world, like trying to keep a job going!
The best piece of advice I can offer in terms of saving money is this: get a single engine CPL and make it the LAST thing you do. (In an airplane).