The traditional answer ranges from a few thousand to around 100,000 years ago. However, recent evidence questions this conservative anthropocentric view and pushes it back much further, perhaps long before Homo sapiens evolved. The best answer today is that language evolved at least 700,000 years ago and likely 2 to 3 million years ago. 

Trationally, due to the lack of a written record, pinpointing the exact date of the first spoken language seemed impossible. Archaeologists believed early humans developed complex communication systems around 100,000 years ago. However, it is clear that the evolution of proto-languages with gestures, basic sounds, and rudimentary vocabulary occurred much earlier.

For a deeper dive into the evolution of vocabulary in human ancestry, take the deep dive: The Evolution of Vocabulary in Ancient Humans.