When to the practitioners of tibetan Buddhism celebrate new years?

During Buddhist New Year celebrations, people take a look on their past lives, and try to identify and rectify mistakes they have made. Also, people buy new clothes, clean up and decorate their households and surroundings, and visit all close friends and families to mark their wishes and share gifts on New Year. One common aspect as reflected in these celebrations is the cheerfulness, splendor, and joy with which they are celebrated. So it is a time of both reflection and anticipation for a good new year.