First 1 billion Years
Earth began to form approximately 4.6 billion years ago. It started with Planetary Accretion. Earth was a ball of hydrogen, helium, and dust that began to collide with smaller bodies and amassed a large amount of rocks and magma. It became about the size of our Earth today. This finished at around 4.3 billion years
At approximately 4 billion years ago, the Earth formed a starter atmosphere, almost nothing like our's today. It also formed an ocean far different from the ones we know today. It wasn't much, but it was the makings of a life-sustaining planet. This was part of the pre-Cambrian Period just like the Hadean Period was. The pre-Cambrian period took up almost the whole first billion years of Earth's formation, so the Earth was basically formed by the pre-Cambrian events.
Basically all planets go through a process called Planetary Cooling. This is how Earth formed. It can take billions of years for a planet to cool. It will eventually form layers around it's core. Then it forms more layers over that to strengthen the interior of the planet. This process is called Outer Core Formation.
This started shortly after the Hadean Period(3.8 billion years ago), and the Earth is actually still cooling; and forming stronger layers. But the Earth stopped changing drastically around 3.6 billion years ago.
Earth's formation was so intense and powerful that it was a molten planet, meaning it was a semi-liquid, magma sphere floating around the Sun. This period was called the Hadean (Hellish) Period. The Earth was under heavy bombardment by remnants of dust and debris. It eventually reached the end of Heavy Bombardment. It then formed more solid and then started to cool as it orbited the Sun.
This began around 4 billion years ago and ended around 3.6 billion years ago.