Burned by LHR and now have brown marks. How long before they start to fade? Or are my legs scarred forever? (photo)

I got burned by laser hair removal on legs. Now i have hyperpigmentation of the marks left by the laser burns. I went to a dermatologist and they prescribed Obagi 4% and i have been using it now for 3 weeks. I haven’t seen a change. I’m afraid my legs are permanently ruined.