Due to multiple factors, expect to potentially pay more when booking in December. For low rates, February can be a great choice for travel to South Africa. Flights to South Africa from Cincinnati in February are about $1,590 on average during February, but can be found for as low as $1,115.
Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Cincinnati to South Africa as you normally would.