The principle is set up along the following two lines of arguments. (1) The existence of life on Earth affirms the crucial experiment for the existence of life. (2) The universe is empirically found to be at least three times as old as life on Earth. The age of the oldest stars in the Milky Way is taken as a lower limit estimate for the age of the universe, and the age of the solar system as an upper limit estimate for the age of life on Earth. Both time-scales are observational facts resting on well-established scientific studies. The first one, on the physics of energy production in stars, and the second one, on the laws of radioactive decay applied to meteorites.
The universe is old enough such that life and a local ecology are expected features of any environment.
Time is life, that is to say, give it time and life is the irremediable end product.