What is the origin/history of "you do you" (or "do you")?

A recent New York Times Magazine piece focused on the expression "you do you" (and its variant "do you"), meaning something like a strong affirmation to "be yourself."

The article associates the phrase with a narcissistic "millennial" culture, implying that it has become popular very recently. Regarding its etymology, the author only asserts: "'Do you' certainly sallies forth from black vernacular, even if the nature of its mundane parts makes its origin Google-­proof," which sounds like an appropriate challenge for this forum.

Some comments on this article have posited that the phrase and usage is older, at least dating to the 1990s. Any thoughts on etymology or history would be welcome.

Solution 1:

The full phrase this originated from is "do you and I'll do me". Another variation is "do you - cuz I'mma do me". The oldest reference to the phrase that I could find is from the song Do You by Funkmaster Flex (featuring DMX), from the album Volume IV, released on December 5, 2000.

This could be a variation of the phrase "do your thing", which has been in use for at least a century.

Solution 2:

1818 Frankenstein ( Mary Shelly) Chapter 19 excerpt.

Do you,’ said I, ‘enjoy yourself, and let this be our rendezvous. I may be absent a month or two; but do not interfere with my motions, I entreat you; leave me to peace and solitude.

That saying is at least 200 years old! Just stumbled on this post after listening to the read of this.