The Romans being Romans took the Egyptian calendar framework and made it their own by applying their normal practical use but even here they took a subtle approach to the order of months -

"Januarius was also called from Janus, and precedence given to it by Numa before Martius, which was dedicated to the god Mars; because, as I conceive, he wished to take every opportunity of intimating that the arts and studies of peace are to be preferred before those of war." Plutarch

http://www.webexhibits.org/calendars...-Plutarch.html

This is the first real divergence between the astronomical event and timekeeping as the orbital position of the Earth implied by the first annual appearance of Sirius which began and ended the Egyptian year was moved to the end of December.

".. on account of the procession of the rising of Sirius by one day in the course of 4 years,.. therefore it shall be, that the year of 360 days and the 5 days added to their end, so one day shall be from this day after every 4 years added to the 5 epagomenae before the new year" Canopus Decree 238 BC

To move forward in terms of understanding requires sometimes a journey back through history to discover just how inspirational astronomers once were and the subtle adjustments made to incorporate astronomy and timekeeping into society.