Unless Google fixes this and saves Christmas. Which we hope it will. The issue has been submitted and acknowledged by Google, so we expect Android 4.2.1 to come sooner rather than later.
The missing December was spotted on a number of devices running 4.2 including the new Nexus 4, the Samsung Galaxy Nexus and the Nexus 7 and 10 tablets. Earlier versions of Android don’t have this bug.
And here is the official thread for the issue on the Android bug tracker. Fingers crossed this gets fixed soon.
source: Android Police
People app in Android 4.2 (right) vs 4.1 (left)