My doctor said 4 weeks before & 3-4 weeks after, ofcourse the longer the better. I think 3 weeks is good enough. I quit 4 weeks before and after completing 3 weeks after surgery i started smoking gradually. I used to be a heavy smoker like 1.5 packs a day, after my third week post op i used to have 2-3 a day then 6 then 10 then 15. I am now over 5 weeks and i am on 15 cigs a day so noway near how much i used to smoke, i am trying to keep it as little as possible to improve my healing. Not planing to exceed a pack ever again! I went cold turkey before surgery, i broke down on day 1 of quitting and had 3 but then never again until my surgery. If you are quitting cold turkey please give yourself a day or 2 before the 3 weeks you have assigned for yourself to quit, incase you break down like me on your first day of quitting. Because if you’re initial intention is quitting 3 weeks before that’s already tight so no room for breaking down and having one