Interesting question, but one that also raises the question of privilege. The super-rich are indeed thinking of ways to prolong their lives indefinitely - and diverting our resources and tech know-how to that end.
In the meantime, growing numbers are being denied access to health care. Death rates of the poor, especially Native American are increasing. To fund the heavenly fantasies of super-rich (moon travel, immortality), environmental destruction, regime-change and wars are being waged on brown and black people around the world to gain control of their resources and markets.
In the middle, is the comfortable middle-class of Western nations. To get their support for the fantasies of the super-rich, our corporate media present those fantasies as if they are common human aspirations accessible to all.
It is indeed no accident that the most famous literary character who lives forever - Dracula - does so by sucking the blood of others!

Tomorrow afternoon seems as good a time as any.

No. I have no way of knowing.

given the way the world is going, pretty sure it would be sometime before the environment becomes unlivable for everyone else, though.

I'm not sure how I will feel about life in 20 years, let alone 20 million.