I did the IR before CPL too. Only because it was February and I knew I'd be twiddling my thumbs due to the wx if I did the CPL first. Also, I wanted to experience some real IMC during my IR not just screens.
I would have to say that it helps to be a bit of a geek - if you can fly approaches in flight sim (MS) while talking on the phone with the wx at minima - having your scan up to speed going into the IR is a big help - the workload is high and your scan needs be automatic by the time you go for test. This will give you some idea if you are ready for an IR. Going into the IR with just the 5 hours of instrument flying from the PPL would be making life reasonably hard IMHO.
However, with the wx as it is right now, I'd be tempted to go for the CPL right now. The fairly regular airmass changes keep the air clean which means good visibility which is crucial for the navigation during the CPL. Save the IR for the winter months when you can enjoy(!) crappy weather and light icing - the experience is invaluable.
Good luck.