The best time to start terraforming a planet is 500 years ago. The second best time is now.
For context, it took an estimated three-quarters of a billion years to oxygenate Earth's atmosphere. Even a speed-run of that is ... considerably longer than a few centuries.
source: https://en.wikipedia.org/wiki/Great_Oxidation_Event
(to be fair, Mars is quite rusty already, it has a head start on the Early Earth in that regard)
In a way, it's a tragedy that human civilization has only emerged at a time when both Mars and Venus have become much more uninhabitable than they used to be.
It seems not entirely unplausible that we have at some point in the scientific chain of custody assumed the “lesser” apes “evolved into” the “more advanced” human.
But a species could easily branch and have the branch lose its geographic portability features (e.g.ability to manipulate environment, most exogenous behavior learning-based) if they are no longer selected for in a particular environment, and I’m not aware of anything in the fossil record that firmly establishes directionality. Am I wrong?