Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Belfast City Airport to Savannah as you normally would.
For a flight from Belfast City to Savannah, you will be flying into Savannah/Hilton Head. Savannah/Hilton Head (SAV) is just 7.4 mi from the center of the city. Savannah/Hilton Head is the only Savannah airport and it handles 0 inbound flights from Belfast City per day. 0 airlines have flights to Savannah/Hilton Head from Belfast City on a regular basis.