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I fear that it would be a bad idea to bring them back into dormancy from here. You may want to plant them in container, and grow them indoors until spring.

Here is an article that will explain how to properly winter these: https://www.gardeningknowhow.com/ornamental/bulbs/dahlia/storing-dahlia-tubers.htm

You can store them just like you would a larger parent bulb. This article will help you: https://www.gardeningknowhow.com/ornamental/bulbs/dahlia/storing-dahlia-tubers.htm

It's best to wait until you see some "eyes" growing so you can determine how to divide the clump, as described in this article:
https://www.gardeningknowhow.com/ornamental/bulbs/dahlia/dividing-dahlia-tubers.htm
Each piece should have one or two eyes after you separate them. Any that are rotten or that don't have eyes should be discarded. It might be hard to determine which is the mother tuber, so don't worry about discarding that.

If it is time to pot up the tuber, soak it in water overnight first. Wrinkles are less of a problem than rot which would be easily identifiable. If it is too early to pot up, place the tuber in peat moss (I use a shoe box; don't use plastic) Spritz the peat lightly - just a hint of moisture. Tuck the box away where it is cool and dry.
Here is a good deal of detail on dahlia care: https://www.thespruce.com/how-to-store-dahlia-tubers-for-winter-2132882

Potassium and phosphorus support roots and flowers. Most soils have enough phosphorus naturally but if you haven't had yours tested, I'd go with a fertilizer with some nitrogen and phosphorus but more potassium. Potassium is the last number in NPK listing. From the plant's point of view, NPK is NPK whether it comes from a factory as granules or organic compost. Look for 5-10-10 or similar. Compost improves soil structure and provides some micronutrients. More on dahlia fertilizer here: https://www.gardeningknowhow.com/ornamental/bulbs/dahlia/how-to-fertilize-dahlias.htm

Dahlias do not like cold soil and they are sensitive to frost. Like tomatoes, putting them out before soil temp. reaches 60 F. isn't recommended. Tubers will not sprout in cold soil and run the risk of rotting. Knowing your zone doesn't tell me your last frost date but you can easily look that up online using your zip code. Your state's cooperative extension service is a good source for information about gardening in your region.