Yes do it. Apart from all of the good safety aspect stuff it sharpens up your flying. Don't worry about the amount of hours you have, I started mine not long after I passed my PPL skills test while the brain was still in training mode. TBH I always saw the PPL as being incomplete without the IMC and night qualification anyway, the PPL bit was just part of the overall package.
The one thing you do have to think about is staying current; I don't mean legally but from a safety point of view. There's not much point getting it and then the next time you fly on instruments is on the renewal. Try and get a couple of approaches in every month; if you're off on a trip go IFR occasionally instead of VFR even if it's a gin clear day; fly VMC on top if it's a crappy overcast day down below instead of plodding through the murk, that sort of thing.
Good luck with it, personally I found it very enjoyable.