No Improvement on Acne Scars (Co2 Laser)

I have acne scars ( shallow ) not too deep but can be seen when looking closly at my face . The plasic surgion said that I need 3 session of co2 laser resurfacing, I already did one treatment but and now after 2 weeks I dont see too much improvment! when I should expect to see improvment though my scars are not deep . Thank you .