With all salvias, all I do prior to frost is just deadhead them. If I deadhead regularly (but do not cut them back severely), I often have flowers until Thanksgiving or even until almost Christmas in a year when the first freeze is really late. As you might have noticed, when you cut them back really hard in the early to mid-fall, all they do is get all rejuvenated and begin regrowing. That's why yours already made so much new growth---because we are so delightfully warm. Or hot, depending on your point of view. If I cut them back to the ground in the fall, I forget exactly where they are, so I leave the dead/dormant foliage/stems/stalks standing until spring. When I see the earliest signs of tiny green leaf buds appearing in late winter or early spring down at the base of the plants, then I cut them back.

This past winter, my autumn sage bloomed almost all winter because we never got cold enough to make it go dormant or to freeze it. I had a hard time deciding when to cut it back because it wouldn't stop blooming. I think I finally cut it back really hard around the beginning of April so I'd have fuller, thicker plants that weren't too leggy.

If I were you, I'd leave it alone and let it grow. It might still be blooming at Christmas with the weather we're having now, and any little bees and butterflies and other hungry beneficial insects will appreciate having the flowers. I still have autumn sage, salvia farinacea and pineapple sage in bloom in my garden and wouldn't dream of cutting them back hard in the weather we're having now. There's still a lot of life left in them at this point. Remember, the plants don't live their lives by the calendar, they respond to their weather/light cycles/climate/moisture.