'First Day' in the Bible

and they summoned the entire community on [the] first day of the second month. And they registered themselves among their clans according to {their families}, according to [the] number of names from {those twenty years old} and above individually,

And it happened, the one who presented his offering on the first day [was] Nahshon son of Amminadab from the tribe of Judah.

On the first day [there will be] a holy convocation; {you will not do any regular work}.

" 'On the seventh month, on the first day of the month, you will have a holy convocation; {you will not do any regular work}. It will be a day for you of blowing trumpets.