When Is Rosh Chodesh Nissan. This special prayer from the shelah hakadosh (rabbi yeshayahu halevi horowitz) to be recited on erev rosh chodesh nissan. Nisan is one of the few months mentioned in the torah by name.
The first day of nisan is rosh hashanah for the following five matters: Rosh chodesh is the first day of the month in the hebrew calendar and is marked by the appearance of the new moon.