I don't know why everyone insists on reflecting on their life at New Year's. It seems to me that there is no worse time to decide what needs improvement in your life. You've just finished the most stressful month of the year. It's cold, the days are short. Why not sit down and figure out what's wrong with you? Won't that make you feel better?
I vote for May. Weather gets nicer, spring really gets going. Now that's a better time to sit down and reflect on life. May is a time of renewal. Why not decide to become a new you when everything else is new too?
So, if you make your New Year's resolutions and they don't quite work out, try again in May. You may feel more like becoming a new person then.
*Note: I'm not that in to introspection anyway. I try to leave the past in the past (except when arguing with my husband, of course).