Nor can we give an answer on time frame, as the time frame is subject to the free will of the humans on the Earth. This is not a settled issue, no more than all the other issues subject to the free will of humans. There is more than one alien race involved. Just as with humans, all entities incarnating in an alien race are not of the same orientation. We got bad public relations from such an incident, and strive to recover from this.
Domination is high on the list.
One can dominate and not be present. This transformation period is already in process, and the time frame cannot be answered impeccably. Self aliens came forward to attempt a coup. They attempted to set in motion occurrences that would benefit them in a large way. War so benefits them.