'First Day' in the Bible

And he shall again consecrate to Jehovah the days of his separation, and shall bring a yearling lamb for a trespass-offering. But the first days are forfeited, for his consecration hath been defiled.

And he that presented his offering the first day was Nahshon the son of Amminadab, of the tribe of Judah.

On the first day shall be a holy convocation: no manner of servile work shall ye do;