If your vehicle is less than 10 years old it only need at most a few minutes.
Modern systems that help make the engine run smoothly constantly adjust for differences in temperature and a fuel injected engine actually runs on air input more than it would on fuel inputs.
On cold mornings I start my car, buckle up and get on my way, easily for the first few minutes giving the car a chance to adjust to the cold.
Remember 0 mph = 0 mpg's.