Well, we are about to celebrate the feast of Janus for who January is named after and his festival took place on January 9, the Agonium. Some try to argue January was named after Juno. But when the calendar was changed, it is more likely that January is named after Janus and June is named after Juno. Janus is usually depicted as having two faces since he looks to the future and to the past. Janus was the god of all beginnings. He was invoked as the first of any gods in regular liturgies among the Romans and he dates back to even the founding of Rome. The beginning of the day, month, and year, both calendrical and agricultural, were sacred to him.
Therefore, when we say goodbye to 2018 and look to the future of 2019, remember one thing. This is a very, very, very old tradition.