The concept of a "year" is based on the time it takes for the Earth to complete one orbit around the Sun. The first year on Earth would correspond to the first complete orbit the Earth made around the Sun after its formation.
The Earth is estimated to be around 4.5 billion years old, based on scientific evidence such as radiometric dating of rocks and the age of the oldest known meteorites. However, it is important to note that during the early stages of Earth's formation, the planet was undergoing intense bombardment by asteroids and other celestial bodies, which made its early history chaotic and difficult to determine precisely.
The formation of the Solar System and the early years of Earth's existence are believed to have taken place over a span of millions of years. Therefore, it is not possible to pinpoint a specific "first year" in the conventional sense.
It's worth mentioning that the modern calendar system we use today, known as the Gregorian calendar, was developed in the 16th century and is based on the birth of Jesus Christ. Consequently, the concept of measuring time in terms of years as we know it does not apply to the earliest stages of Earth's history.