Variks speaks as if he was present during the post-Whirlwind division of Fallen Houses whenever House Judgement was destroyed. We do not know the exact time this occurred, but we know that it happened before the Fallen entered our system. The Fallen have been in our system for several hundred years (since the Dark Ages started). So it's actually quite possible that Variks is nearing or above 1000 years old, especially seeing how our grimoires on the Fallen Archons and Kells provide evidence that they've all lived even longer than that Fallen are already known to have much longer life spans than even the 300-year-old-spanned humans of Destiny