Exodus 12:2

The beginning of months] The exodus is regarded as an 'epoch-making' event (cp. Judges 19:30; 1 Kings 6:1), and to mark its importance the month in which it occurs is to be reckoned the first month of the ecclesiastical year. This is the month Abib (see Exodus 13:4; Exodus 23:15; Exodus 34:18; Deuteronomy 16:1), i.e. the month of ripening ears, and corresponds to the end of March and the beginning of April. After the exile it was called by the Babylonian name of Nisan: see e.g. Nehemiah 2:1

Esther 3:7. The sacred feasts were computed from this date: see Leviticus 23:4; Leviticus 23:15; Leviticus 23:24; The civil year began in autumn with the first day of the seventh month after Abib, called by the Babylonians Tishri and in OT. Ethanim: see 1 Kings 8:2. With this change of reckoning may be compared the reckoning of the Christian Year, which begins with Advent, and of the Christian Week, which begins with the Lord's Day.