I started my MEIR recently and am planning to do the CPL after. The school i am at suggests doing it this way. During the last 2 weeks they have only been doing IR training as the weather has been crap for CPL. The IR is hard work so far but not impossible. Everything is done at a reasonable pace and is taken from a "back to basics" from the start of the course. Im assuming you've done your ATPL's?? If you have the hours requirements then start with the IR. Start with the CPL and you'll still be at it for months with the weather. You can also knock off 10 hours of cpl training if you do IR first.