What are the chances of getting a dry socket from smoking a single cigarette 8 hrs after wisdom teeth are pulled?

You can smoke 12-24 hours after extraction but then again, you have to take into consideration many factors, for instance: was it a difficult extraction? was it in the maxillary (upper) jaw or in the mandibular (lower)? Do you take contraceptive pills? If you're a smoker, had a difficult extraction (tooth got broken or was difficult in getting it out), take contraceptive pills and had an extraction in the lower jaw, then you'd better refrain from smoking for a while. Dry sockets are more common when lower pre/molars are extracted since there are less blood vessels. This means that less blood is travelling to clot the socket and therefore the bone and surrounding tissues get infected.

Saline helps alot to disinfect and keep the socket clean during the following days.