I keep food/water in the coop as well. It's always worked for us. The chickens like to eat and drink early, but I prefer to let them out after the crepuscular predators finish their dawn hunt.I kept mine in the coop until temps went above freezing. They don't like being kept in, but the outdoor water was frozen. The night before, I put the feeder with plenty of extra food, in the coop and an extra waterer, to make sure they have plenty of breakfast to get them through until it warms up enough to turn them loose. Luckily, here, the freezing temps are not typical and don't last too long and the coop is pretty big and well ventilated so they can spread out a bit and be comfortable.
Are you in upstate SC? If so, we're probably only 2-3 hours away. Stay warm!
At this moment, with 2/3' of snow on the ground and 10°F/-12, I'm wishing we lived 2-3 hours further south as well. High here today is 19F, dipping down to 1 overnight. Over it.