Everything from the events leading up to the fall of Numenor to the end of the Second Age takes place in Elendil's / Isildur's lifetime (even if Elendil's lifetime lasted over three hundred years).

The Second Age is basically three thousand years with very little recorded history in any more detail than 'Numenoreans interact in various ways with the less advanced humans in Middle Earth while Celebrimbor makes the Rings', and then a whole lot in 1 or 2 centuries at the end. But then again, the Third Age is quite similar, though to a lesser extent as we know a bit more about the history of Gondor/Arnor.

I'm not too confident it will be great and I might've preferred that they just leave Tolkien alone, but if they were going to make a series anyway, I don't think it was a bad idea to pick those final centuries of the Second Age as a setting. Of course there's less going on than in the First Age, but that may not be a bad thing if you're trying to attract a wider audience and don't want to have to do too much exposition in the beginning. Plus, the Atlantis-like story of the downfall of Numenor is easy to make both gripping and relevant to a contemporary audience.