Derek Sivers hits the nail on the head for me in his blog post, Time is personal. Your year changes when your life changes:
Your year really begins when you move to a new home, start school, quit a job, have a big breakup, have a baby, quit a bad habit, start a new project, or whatever else. Those are the real memorable turning points — where one day is very different than the day before. Those are the meaningful markers of time. Those are your real new years.
To force these celebrations on universal dates disconnects them from the meaning they’re supposed to celebrate.
Happy New Year people, whenever it is you may be celebrating.