CPL first then IR is the natural progression. Start with the (predominantly) VFR skills of the CPL and then move on to the more demanding IR. Furthermore, CPL training is generally cheaper so it makes sense to build your experience at this level before moving on to the much more expensive IR. It may be theoretically possible to do IR first then CPL and achieve an overall hour saving but for every one success of this route I guarantee you there are a half a dozen for whom it costs much more. Also, reverting back to looking out of the window after you've had your eyes glued to the instrument panel will take a little while in itself.
Most schools go for CPL then IR. Ask yourself why.