John Gill Commentary Ezra 6:19

"And the children of the captivity kept the passover upon the fourteenth [day] of the first month." — Ezra 6:19 (ASV)

And the children of the captivity kept the passover upon the
fourteenth day of the first month .
The month Nisan or Abib, which was the month following that in which the temple was finished, (Ezra 6:15) , this passover was kept at the exact time the law commanded, (Exodus 12:2Exodus 12:6) .