According to the best scientific measurements we have, time began 13.7 billion years ago. Hard to comprehend, isn't it? Maybe it will help if you think of it this way:
If the Big Bang occurred on the first second of January 1 and today is the last second of December 31, then:
The Milky Way came together in March...
The Sun and the planets in August...
The first single-cell organisms appeared in August...
The first vertebrates on December 17...
Dinosaurs on December 24...
Modern humans at 11:54 on December 31...
And recorded history began in the last 10 seconds.