The K04 is oil cooled, and thus it has a seal in it. When the seal goes from 1100°F to 70°F after sitting in your driveway overnight, expect it to change size slightly (think thermal coefficient of expansion). When the seal is cool, a very small amount of oil leaks past it, and into the turbine itself. So, when you start the car, you instantly hit that oil with hot exhaust gases, so it burns. At the same time, the turbo starts to warm up, and so the seal starts to expand, thus appropriately sealing again. Voila... puff of smoke that goes away after startup.

/that is all.