Had fulfilled the days - The days of the Passover. These were eight days in all - one day for killing the paschal lamb, and seven days for the observance of the feast of unleavened bread, Exodus 12:15; Leviticus 23:5-6.
Related Commentaries of Luke 2:43
Luke 2:43
43 And when they had fulfilled the days, as they returned, the child Jesus tarried behind in Jerusalem; and Joseph and his mother knew not of it.