Smoking in the first 5-7 days can significantly increase chances of infection or dry socket. Smoking after that up to 6-8 weeks can slow down the healing process with higher chances of infection. Smoking after 2.5 to 3 months, once the site has completely healed, is probably ok.
The longer you can hold off the better but the first 24-48 hours is crucial. After this time period the blood clot should have formed and healing has started to occur. Although smoking at any time will still delay healing after the 48 hour time period you should be fine.