Zydecajun,
The shelters are located fairly convenient mileagewise and while some are newer and nicer, none are really bad (if you don’t want to stay in them, tent nearby with usually other hikers and good water supplies.
In Georgia the weather can change very much, within a day, prior to around April 1ST. You could have very warm days to nightly lows in the single digets just depending.
Look at some of the gear lists of prior and current hikers. You will not need a lot of clothes as you hike, but will need warm clothes for breaks, around camp and sometimes to supplement your bag.
Hope this helps and also read “Bono” as jt stated. Good journals and accounts of weather for January.
This section is a beautiful and fun section, but take it easy in the start with mileage, I would just target shelters. Have a great hike !!
Happyhiker