'First Day' in the Bible

In the Sinai desert, the LORD spoke to Moses inside the Tent of Meeting on the first day of the second month of the second year after they had left the land of Egypt. He said,

On the first day Amminadab's son Nahshon, from the tribe of Judah, presented

"On the first day of each month, you are to offer a burnt offering to the LORD consisting of two young bulls, one ram, and seven one year old lambs, all of them without any defects,

"On the first day, you are to hold a sacred assembly. No servile work is to be done.

"On the first day of your harvest season, you are to hold a sacred assembly when you present your first fruits during the Festival of Weeks. No servile work is to be done.

"You are to hold a sacred assembly on the first day of the seventh month of each year. No servile work is to be done. It's a day of blowing trumpets for you.

Then Aaron the priest ascended Mount Hor in obedience to the LORD's command and died there, in the fortieth year after the Israelis had come out of the land of Egypt, on the first day of the fifth month.