We just had some OFA finals done a couple of weeks ago, so are in the same boat.
It took 8 days from the date the radiographs were taken (rads were done over the weekend) until the confirmation e-mail came saying that OFA had received them. In the e-mail, it stated that it usually takes 2-3 wks after that to get the final results based on the fact that now the films have to be reviewed by the 3 different radiologists (often in different states/locations).
When we had prelims done on the same dog, it only took 7 days total from having the radiographs taken until seeing the results up on the OFA site. There is only one radiologist who views the prelims, so they're able to get the results much more quickly.
Mine was 2 weeks from when they received the x-rays and that was in October. They were posted on-line the same day I recieved the certificates in the mail.