It's impossible to pinpoint the exact moment the first fossils were discovered, as prehistoric humans likely stumbled upon them long before recorded history. However, we can look at early documented discoveries:

* Ancient Greece and Rome: Philosophers like Aristotle discussed fossils, attributing them to natural processes.

* China: Fossils were incorporated into traditional medicine and art, with notable examples from the Han Dynasty (206 BC - 220 AD).

* Renaissance: The rediscovery of classical learning sparked renewed interest in fossils. Leonardo da Vinci made accurate observations about fossils, suggesting their organic origin.

The 17th and 18th centuries saw a growing scientific understanding of fossils:

* Robert Hooke: In the late 1600s, he published detailed observations of fossils, comparing them to living organisms.

* Nicholas Steno: In the mid-1600s, he established the principles of stratigraphy, which helped understand the sequence of fossils in rock layers.

* Georges Cuvier: In the late 1700s and early 1800s, he made significant contributions to paleontology, demonstrating the extinction of ancient species through fossils.

Therefore, while we can't say when the *very* first fossil was discovered, we can point to these periods and individuals as marking key milestones in the understanding and study of fossils.