Dawn of time

The phrase "the dawn of time" was sometimes used to refer to pre-human eras of Earth's history.

Dawn of the universe
The Seventh Doctor once used the phrase synonymously with the beginning of the universe, "the beginning of all beginnings", explaining to Ace that first came the forces of good and evil, then chaos, and the birth of time, matter and space. Both forces shattered as the universe exploded outwards, leaving behind only echoes until, eventually, the evil force resurfaced as what became known as Fenric. (TV: The Curse of Fenric)

The Planet One, "the oldest planet in the universe", had a diamond cliff with a "message from the dawn of time". The Eleventh Doctor took Amy Pond to Planet One to see the cliff face so that the TARDIS would translate the writing. When they arrived the writing revealed itself to be a message from River Song reading "Hello Sweetie" with a set of temporal co-ordinates, "ΘΣ Φ ΓΥΔϟ". (TV: The Pandorica Opens)

The Beast claimed to have "woven himself in the fabric" of life since the dawn of time. (TV: The Impossible Planet)

Dawn of the Earth
Jack Harkness identified the fairies native to Earth as beings from the dawn of time. (TV: Small Worlds)

Vastra, a Silurian, introduced herself to Alice as a "lizard woman from the dawn of time". (TV: The Snowmen)

The Twelfth Doctor referred to the Clockwork Droids under the command of the Half-Face Man, who had been on Earth since the Age of the Dinosaurs, as "rubbish robots from the dawn of time". (TV: Deep Breath)

Human scientists experimenting with time travel once managed to send a camera back millions of years in an attempt to photograph the first living thing stepping onto dry land. They referred to the results as "sounds and photos of the dawn of time". (COMIC: Dr. Who's Time Tales)

The Fourth Doctor told Mike Yates about having seen "skulls from the dawn of time". (AUDIO: The Stuff of Nightmares, TV: Image of the Fendahl)

The Thirteenth Doctor observed that the Sontarans' Temporal Offensive would have made Earth a Sontaran outpost from the dawn of time, erasing its prior history. (TV: War of the Sontarans)

Dawn of mankind
Cheryl Farley noted that, from the dawn of time, man had looked up to the stars for guidance. (TV: Secrets of the Stars)