I just bought the car, but from the records looks like about 7 months ago.
Update on when it happens too - it's totally temp related. Yesterday was 5 degrees out and the car lives in a heated garage. The creaking didn't start until I was 30 minutes to work.
At the end of the day, car having been in 5 degree weather all day, the car groans and creaks like crazy for most of the drive. Finally quieted down some by the time I got home - but even then, still some creaking.