Do you have any idea of how large as the area controlled by the andal kingdoms in essos before the arrival of the valyrians?

“Controlled” is difficult to say, because the Andals seemed to have occupied territory that was also occupied by the Rhoynar, the Valyrians, the Ibbenese, etc. Also, the Andals weren’t a settled people, but migrated. 

But the territory from the hills of Andalos to the Axe seems roughly the width of the Riverlands.