It's generally believed that the Moon formed within a few hundred years after the Earth itself formed. This timeframe is based on the Giant-Impact Hypothesis, the prevailing theory for the Moon's origin.

Here's a breakdown:

* Giant-Impact Hypothesis: This theory suggests that a Mars-sized object, called Theia, collided with the early Earth. The debris from this collision coalesced to form the Moon.

* Timeframe: Estimates for the time it took the Moon to form range from a few weeks to a few hundred years. This depends on factors like the size and velocity of Theia, the amount of debris generated, and the rate of accretion.

While the precise timeframe remains a subject of ongoing research and debate, it's generally accepted that the Moon formed relatively quickly after the Earth's formation.