There's no "right answer" for this question, but it is black and white. As in it's in the contract, typed in black on white paper. Time of possession is written into the contract in Georgia and that's when your keys will be delivered. If the contract says "at closing" the time can vary a bit from the exact moment that you are sitting at the closing table at the attorney's office for funding or wire transfers to hit the bank.
But when I read today that in some states you have to wait for documents to be recorded, that's not the case in Georgia. If at the closing table the buyers have signed the deed and the loan is wired to the attorney and bank has released those funds and down payment has been wired or delivered by cashier's check then the seller walks out with a check and the buyer walks out with the keys from the same closing table.
Of course the contract doesn't have to say at closing. Some sellers who live in their home full time request several days after the closing for possession. Sometimes those sellers need the funds from closing on a home they are selling to purchase a new home and have to make that purchase before they can move. The time you get the keys is a matter of contract negotiation. Some listings in the MLS state the seller will require x number of days after closing before possession changes hands. A buyer doesn't have to agree to that, but a seller doesn't have to sell if terms are not acceptable in the contract including time of possession.
But in typical situation in my market where homes are second/vacation homes it's not a problem for the seller to move their personal property out prior to closing so that possession can happen right there at the closing table. That's the scenario we see most often, again in MY market. Doesn't happen every time, but in my experience about 95% of the time it does. If you are a seller who will need time after closing be sure to tell us when you list. If you are a buyer who will need to have the keys to drive over a moving truck after closing please tell us up front when you start your home search.