The kalends is the first day of the month in the Roman calendar. When Roma Antiqua followed a lunar calendar, the kalends occurred when the slightest crescent of the new moon appeared in the sky. However, after the calendar of Roma Antiqua had undergone numerous alterations over the years, the kalends became the first day of the month instead; derailing it from coinciding with the new moon.
History of the Ritual
On this day in Roma Antiqua, the Rex Sacrorum was accompanied by a secondary pontifex in making a sacrifice in the Curia Calabra on the Capitoline Hill. This sacrifice was made to Iuno and also honored Ianus; the prevailing idea being that Ianus, as the god of good beginnings, assisted Juno in giving "birth" to the new month.
In the course of this sacrifice, the name of Juno Covella was invoked as the date of the Nones was announced. After the Rex Sacrorum fulfilled his duties in performing this sacrifice, his wife the Regina Sacrorum would perform a sacrifice to Juno in the Regia in the Forum.
vindicat Ausonias Iunonis cura Kalendas;
Idibus alba Iovi grandior agna cadit;
Nonarum tutela deo caret. omnibus istis
(ne fallare cave) proximus ater erit.
omen ab eventu est: illis nam Roma diebus
damna sub averso tristia Marte tulit.
haec mihi dicta semel, totis haerentia fastis,
ne seriem rerum scindere cogar, erunt. 
The worship of Juno claims our Italy’s Kalends,
While a larger white ewe-lamb falls to Jupiter on the Ides:
The Nones though lack a tutelary god. After all these days,
(Beware of any error!), the next day will be ill-omened.
The ill-omen derives from past events: since on those days
Rome suffered heavy losses in military defeat.
Let these words above be applied to the whole calendar,
So I’ll not be forced to break my thread of narrative. 
- ↑ Ovid Fasti, c. 1 ln. 55 - 62 
- ↑ Ovid Fasti Book 1, A. S. Kline trans. http://www.tkline.freeserve.co.uk/OvidFastiBkOne.htm