How long did it take for anatomically modern humans to develop a language?
Homo sapiens always had language, and their ancestors of a different species had language before them. I don't know what you're thinking, but... that's not how it works.
Little is known about the timing of language's emergence in the human species. Unlike writing, speech leaves no material trace, making it archaeologically invisible.
I suspect that language preceded Homo sapiens. Chimps have a vocal language. So do dogs and many birds.