Hi,
Generally, post-acne PIH will fade on its own after several months. The key is to control the active acne as continued active acne causes more new blemishes and scarring. Check out the Acne section for details of the various acne medications that work.
To hasten the clearance of post-acne PIH, pigment lasers may help although treatment response is variable and often several treatment sessions are needed.
In my opinion, early or later treatment of post-acne PIH does not significantly alter treatment outcomes.
In conclusion, for the best outcome, focus on controlling the cause of the PIH i.e. active acne, well.
Hope this helps!