My wife did it like that and had no problems, they are two completely different skills and different types of flying.
Most people prefer to just get all the VFR stuff out of the way first so they don't have to go back into all the drudging around the countryside visual map reading in a PA28 after they've got their IR they can focus on the MCC or type rating or whatever it is they're going to do next, and they're still in the IFR mindset.
But if it's January, it sometimes makes a lot of sense to get the IR out of the way first, because you'll just have too many days where you can't get any VFR flying. Then come April or May when the IR is finished, you'll have a better chance of getting more than one day a week nice weather for the CPL
