New Year should be the arising event, meaning the beginning of a new, better part of the year, like the arrival of spring that signals the impending warm weather and bloom after cold, often boring winter. If New Year begins three weeks before the arrival of spring, then New Year would be a arising event, but it would be even more arising if New Year begins with the beginning of spring. So I would have spring began about 2nd or 3rd day of the year.
A year before the year that begins on March 1, the preceding year will last 14 months, two months longer than usual. 2215 will be the first year in which it begins on March 1, so 2214 will last 14 months or 443 days, 78 days longer than a common year. So it means that each of the two extra months will last 39 days, instead of usual 30-31 days. Since there essentially be second January and February in a year, the two extra months will receive virtual names: Mortuary (after Morta, the minor Roman goddess of death) and Cupruary (after Cupid, the Roman god of love).
Beginning in 2215, the year will begin in March and end in February, and the ordinals of every month will downgrade by two. It will be the first time that a year begins in March since the Romans added January and February. For example, months named after numbers, September through December will be in line with the ordinals after the change. September through December will then be the seventh through tenths months of the year.
Time change that begins the dayEdit
I also propose that new day should begin around dawn instead of middle of the night as it currently is. This plan will also be implemented on New Year's day of 2215. For a change, New Year's Eve 2214 (which would be on Cupruary 39) will last 30 hours, six hours longer than usual, 24-hour day. On Cupruary 39, 2214, AM and PM will have 15 hours, and midnight will be 15:00 AM while noon will be 15:00 PM, which will be just over two hours till nightfall. The reason about this change is same basic reason for New Year date change is that dawn is the arising event. It is noted that dawn is the daily equivalent of the arrival spring. Starting on New Year's Day, there will be new terms for the halves. AM (ante-meridiem) and PM (post-meridiem) will be replaced with DH (Day Half) and NH (Night Half). After this change, twilight periods will be around 12 or 1, instead of around 6 or 7 as it currently is.
Around equinoxes, dawn will take place around 12 DH and dusk around 12 NH. But during the longest days of the year, daylight can last from around 10 NH till around 2 NH for those living in mid-latitudes. During the shortest days of the year, darkness can last from around 1 DH till around 11 DH for those living in mid-latitudes.