I know I'm a bit late, but I'll try to compensate with some unexpected history.
Has anyone ever wondered why we celebrate the new year on the first of January? It has nothing to do with religion, may it be christianity or more traditional (I hate the word "pagan", but I may digress) religions, nor with the seasons. January takes place after the winter soltice and we are far from the beginning of spring.
It actually has much to do with something I'm very familiar with: the political organisation and the wars of the roman republic.
At first, the roman new year was beginning on the first of march. The god of war month meant back in the republic that the consuls (the two "presidents" of Rome) took their offices. The yearly elections took place in december, but the consuls took power in march. Then, the republic would call its citizens to arms. A month a two later, Rome was ready to wage war. Yes, back then, Rome's armies were conscripted amongst the citizens. They would only become professional soldiers around 110 BC. The mandate of the consuls was to last until december, when new elections would be held.
When you think about the beginning of the year in march, it has some logic. Spring is the time for war. Farmers could leave their crops grow. Wars ended in late august so the men could come back to harvest their fields and prepare for winter. This system was working very well until the wars of the republic took its men to the far lands of Asia and Spain.
One more thing, with the beginning of the year in march: september is actually the seventh month of the year! October, november and december follow the same logic. Yes, the romans could count to ten correctly ;).
But everything changed in 154 BC. The Lusitanians, one the most fierce tribe in Spain, began an open revolt against Rome in december, leaving the roman allies desperate for help. But the legions would only be coming a few month later. The Lusitanians hoped for an easy victory.
The roman senate took the threat very seriously. They asked the newly elected consuls to take their charge sooner, on the first of january, so they could muster the men immediatly and leave to war at once. And so, Q. Fulvius Nobilior and T. Annius Luscus took their office three months before what was normally done, and departed with the legions and took the Lusitanians by surprise.
Being able to begin war two to three months earlier was something that the senate saw as very convenient. And so, since 153 BC, the new political and military year takes place on the first of january. And that's one of the many thing that Rome passed on to us.
Well, admit it, it was quite a revelation, right? ;) I hope I didn't bore you to death, but I thought it was worth mentionning.
On a lighter note, may I leave you with some music?
https://www.youtube.com/watch?v=5JRYzaFUvz4