The fallen angels were driven out of heaven by the son of God,and the angels allied with him, down to earth, even to the abyss, but before that some even became men to marry women, contrary to the will of God, and were bound in chains.
It seems that they were not immediately cast out of heaven, because even in their fallen state they were made agents of God (cf. the book of Job where Satan goes to and fro). In that sense it is like high rulers, which God allows to serve his purposes before they are cast down.
When Christ came, he said he saw Satan fall like lightening from heaven.