• Universe is 13.7 Bya +/- 2% old
• THe first elements Hydrogen, Helium and Lithium are formed from 240,000 - 300,000 years after the big bang.
• The cosmic microwave background (CMB) radiation is created about 380,000 years after the big bang.
• Early active galaxies, and population III stars started to form 300 - 500 million years after the big bang.
• Heavier elements were created sometime after 500 million years by massive stars and supernovas.

Books:
The Inflationary Universe", 1997, Alan Guth