Also, this is still applicable:
If you use the app, you can check in "my trips". Gate assignments for the incoming flight to ATL will usually not be given until a couple of hours before arrival, so you may or may not be able to get the info before you leave PNS, and of course sometimes it will change. Once you hit the ground in ATL, while you're taxiing to the gate, though, the app should be pretty accurate.