Like I said just before, you shouldn't wait until after CPL training to take ATPL theory
Why ?
ATPL theory takes 9-12 months for a normal person with a normal rythm. Which gives you an idea about the volume of it.
So say you pass your IR exam. It is valid for one year.
One year within which you will be doing MCC training and re-learning ATPL theory. So you haven't even finished your training and you already need to spend about 1k more to renew your IR rating.
Plus, you have to learn CPL theory and IR theory before your CPL/IR
So basically you will be doubling the amount of theory that you have to learn
Not exactly double because it will be easier to learn the second time, but you will have to learn all the details twice. Which is not very rational.
ATPL theory is CPL theory + IR theory + some other little things