The AP and the New York Times are both predicting a total turnout of 4.2 million to 4.3 million votes. Just under 5 million votes were cast in November, so that means we could see runoff turnout at about 85% of Election Day turnout. By contrast, in 2008, which was the last time Georgia hosted a Senate runoff, turnout in the runoff was just 57% of Election Day.
— Daily Kos Elections
Keep in mind, however, that rural counties, which tend to favor Republican candidates, are only just now beginning to be counted. Stay calm, keep a weather eye out, and be patient.