The Winter solstice was thought to occur on December 25. January 1 was new year day: the day was consecrated to Janus since it was the first of the new year and of the month (kalends) of Janus: the feria had an augural character as Romans believed the beginning of anything was an omen for the whole. Thus on that day it was customary to exchange cheerful words of good wishes.
For the same reason everybody devoted a short time to his usual business, exchanged dates, figs and honey as a token of well wishing and made gifts of coins called strenae. Cakes made of spelt (far) and salt were offered to the god and burnt on the altar. Ovid states that in most ancient times there were no animal sacrifices and gods were propitiated with offerings of spelt and pure salt. This libum was named ianual and it was probably correspondent to the summanal offered the day before the Summer solstice to god Summanus, which however was sweet being made with flour, honey and milk.
Shortly afterwards, on January 9, on the feria of the Agonium of January the rex sacrorum offered the sacrifice of a ram to Janus.

Happy new year to all! wishing ever one a prosperous 2018 [if you put God first and mind your business]

lemme consult the gods on this very matter