Shabbath HaChodesh precedes the first of the Hebrew month of Nisan during which Pesach is celebrated. On the first day of Nisan, G.d presented the first commandment of how to "sanctify the new moon" (kiddush hachodesh) for the onset of Rosh Chodesh and so Nisan becomes the first month of the Jewish year (counting by months.).
Shabbath hachodesh black and white drawing