They did not see one another, nor did anyone rise from his place for three days, but all the people of Israel had light where they lived.
#exodus 10:23 #bo

Why didn't the Hebrews leave immediately after the three days of darkness while Egypt was weak? God didn't tell them to leave then because he wasn't through with Pharaoh yet. It was only right before the tenth plague that God told the Hebrews to prepare to leave. Judgment doesn't end until judgment is complete.