I prefer around 25°F for cold stabilization. How long is a complicated question. Usually crystals precipitate out within a few days. But keeping it for at least two weeks is commonly done to make sure.
I asked because I've had wines outside for almost 2 weeks now. Temps have been in the mid 20's in the stairwell but we are having a warm spell again. I was planning on leaving out til the 18th which would be just about a month. The good thing, even with the temps getting to 60 yesterday, it still remained in the 30's in the stairwell.
I generally shoot for a month. Checked the stairwell temp after work and it's at 44. Hoping it gets cold again soon. (Not that I want the cold I can handle 65 on the last day of January.)