The hogs are there...its just a matter of how hard you want to work. In January there are few things to eat other than rooting in the swamp daylight to midday, and then going to the feeders in the evenings before dark.
They sleep in the swamp, usually in cane thickets, and can be stalked up on and shot in their beds or as they leave...all during hte day.
January is a good time to kill pigs. September, October, and May probably rank as the best months of the year, but the rest are great as well. We don't have much time during the year when things would be called S-L-O-W. I would not recommend full moon weekends as great times to hunt.