I overwinter more than 200 potted hostas every winter. Annually I wait until Thanksgiving and I tip over every pot to assure that water does not sit on the pots when thawing and freezing occurs in early spring. Over 90% survive.
This winter I have over 1,000 potted hostas, and after consistent freezing temperatures, I am going to place many in heavy plastic bags to avoid the rain in the spring.
A few winters ago I had some in larger pots that I removed from the pots and placed them in plastic bags, and placed them in an unheated garage. All survived.