Answer:
The Kalends of February would be February 1st.
Explanation:
The names we use for the months of the year come from the names the Romans used. There are three fixed times in each month, and all dates are given in reference to these fixed times.
The first day of each month was called the Kalends (Latin Kalendis).
For most months of the year, the fifth day was called the Nones (Latin Nonas) and the thirteenth day was called the Ides (Latin Idus), but in March, May, July and October, the Nones and the Ides were the seventh and fifteenth days.
For more (and important) information about the Ides of March, see Related Question below.
Additional information:
In Roman computation three days in the month were used for counting the date. These three were the Kalends (1st day of the month), the Nones (the 7th day in March, May, July, and October, the 5th in the other months), and the Ides (the 15th day in March, May, July, and October, the 13th in the other months). The days were counted before, not after, the Kalends, Nones, and Ides. Thus, Jan. 10 was the fourth day before the Ides of January or the fourth day of the Ides of January, because the Romans counted inclusively. Jan. 25 was the eighth of the Kalends of February, Feb. 3 was the third of the Nones of February. Feb. 23 was the seventh of the Kalends of March and remained so when an intercalary day was inserted every fourth year between it and Feb. 24; hence in a leap year there were two days counted as the sixth of the Kalends of March. The leap year was therefore called bissextile [Lat.,=sixth twice]. There is a legend that alterations in the length of the months were made later by Augustus to flatter his own vanity, but there seems to be no foundation for this story.