It's impossible to say exactly when Spica was first spotted in the sky. Here's why:

* Spica is a very bright star: It's one of the brightest stars in the night sky, making it visible to the naked eye since ancient times.

* Early humans were aware of the stars: Ancient civilizations like the Babylonians, Egyptians, and Greeks observed and documented the stars.

* No written records exist from the very beginning: The oldest known records of star observations are thousands of years old. It's likely people observed Spica long before that, but we have no way of knowing for sure.

So, while we can't pin down the exact date, we can say that Spica has been observed and recognized as a significant star for millennia.