The month Nisan is the first month of the Jewish calendar. In the year 445 BC (when the events of this paragraph occur), the month Nisan spanned the four-week period beginning on April 13 of the Gregorian calendar. Nisan is four months after the month Chislev, mentioned in Nehemiah 1:1. Nehemiah had continued fasting and praying
day and night
during this four-month period (Nehemiah 1:4, Nehemiah 1:6).
1 In the month of Nisan, in the twentieth year of King Artaxerxes, when wine was before him, I took up the wine and gave it to the king. Now I had not been sad in his presence.