Nephi's selection of an example is interesting. Of course it was a well known example of the miracle of the deliverance of Israel from bondage, but there were several miracles performed by the Lord, both during that Exodus and at other times. Of all of the stories he could have chosen, Nephi selects a story in which the Lord killed the enemy. Nor does Nephi stop short of making the comparison between their task and the drowning of Pharaoh, for in verse 3 he indicates that they are "to destroy Laban, even as the Egyptians".
Nephi may not have had any conscious plan to find and kill Laban, but if we can assume that his speech to his brothers was inspired, then the Lord provided a precursor to the events which followed.