If your car had a turbocharger, I would say change it out right away. However, your car uses thin oil to get that last little bit of gas mileage for the manufacturer to meet the CAFE standards.
I would change it out soon if you live in a cold climate though, and put in what the manufacturer recommended. A 0W20 HAS to be synthetic; you cannot formulate a decent 0W20 from normal mineral oil.
Once the warranty runs out, I would use 0W30 synthetic, which will give you the maximum engine life with only a tiny penalty in gas mileage.