Atheists, if you were dropped of in Antarctica naked as day one, how long would it take you to grow fur?

Actually, evolution doesn't work that way. A single person doesn't evolve within a lifetime, evolution takes thousands, if not tens of thousands, of years. And, most likely, people wouldn't evolve fur coats, since they wouldn't be necessary. People can use furs, clothing, shelter, etc to keep themselves warm. In order to evolve a natural fur coat, most likely, tribes of humans who never wear any type of clothing would have to slowly migrate to a colder climate over the course of thousands and thousands of years.