Hi Peter!
Check your water temperature. If it is anywhere above 50 degrees F., you can start doing 15-20% changes (drain the water first, add dechlorinator, add back fresh water) every three or four days right now. Given that you live in Georgia, it is likely that your water temperatures stayed well above freezing all winter, and leaving your filters on all year and keeping up with your usual water change program through what you consider cold weather (Sorry, it's too easy a shot. Bad Bob! No cookie!) is perfectly feasible.

The advice from this quarter tends to be geared towards upper Midwest ponders, since the Midwest Pond and Koi Society is based in the Chicagoland area. Our ponding season is short, usually from May to early November, and our winters are bitterly cold. We all envy you your position south of the Mason-Dixon Line!