When did each Voidborn arrive to Runeterra?

And what have they done since then? I know the Void hasn't recieved its region update yet, but we alredy have some canon information.

From Vel'Koz's bio: "It is unclear if Vel’Koz was the first Void-spawn to emerge on Runeterra, but there has certainly never been another to match his level of cruel, calculating sentience". I assume this could be the starting point, probably after the big portal was opened in Icathia (not sure about this, as Aurelion's story involves a portal and it happened before the sun disk of Shurima was finished, way before the event of Icathia). So I'd say Vel'Koz has roamed around Runeterra for about a thousand years (?), gathering information for the Void.

Rek'Sai seems quite old too, as she and her kind gave its name to a desert in Shurima. The Sai voidborns seem to be digging a huge portal, as it was shown on her color story.

I don't know when did Kog'Maw arrive, but he is essentially a child and he doesn't seem to have moved from Icathia, so I guess he hasn't been here for longer than a century (?).

I'd say Kha'Zix isn't quite old neither, as he quickly evolves and he is around the power level of Rengar at the moment, and even if the vastaya is a great hunter, I don't think he could stand a chance againt Rek'Sai, for example. The longer Kha stays on Runeterra the stronger will he become.

Finally, Cho'Gath . He is supposed to be "The Terror of the Void", and he grows giant as he eats matter, but shouldn't such creature be extremely notorious for the whole planet? What does he do and where is he? He isn't mentioned in any other champion's lore. I think his concept is quite outdated (when the summoners were canon he hadn't totally crossed the portal, so it made sense), and he doesn't fit the lore at the moment.