If you stay near Stover Creek on night 1, then Justus Creek on night 2, and Lance Creek on night 3, you'll probably just want to get off the trail at Neel's Gap at the end of the 4th day. I would, anyway, being a guy slightly overweight fella that doesn't get on the trail as much as I'd like these days.
I see that you are young guys, so maybe the up and down doesn't have the same effect. The elevation in Georgia isn't bad, but it does surprise many beginning hikers. The climb up Blood Mountain, for example, does go on for quite a while.