Most of these ideas of what "pimp" is come into the mainstream through hip-hop, and pimping first came into hip-hop in the late 80's. In 1987, Ice-T released a song called "Somebody Gotta Do It (Pimpin' Ain't Easy!!!)" and two years later Big Daddy Kane released the more famous "Pimpin' Ain't Easy". While Kane never (to my knowledge) claimed to actually have engaged in prostituting women, it was an important part of Ice-T's biography. While some of the more outlandish parts of Ice-T's biography seem doubtful, it seems certain that he actually engaged in pimping women just as slightly later rapers Jay-Z and the Notorious BIG actually engaged in low level crack sales.

To my knowledge, Ice-T the first rapper to parlay claims of literally pimping women into hip-hop prominence, but even before he broke big, many the "classical" ideas of how a pimp looked and acted were in place. Ice-T was influenced heavily by the literary pimps of the 60's and 70's, particularly Iceberg Slim. Ice-T's name is even inspired by Iceberg Slim's, and he named this third studio album The Iceberg/Freedom of Speech... Just Watch What You Say!

There's a genre of publishing simply called "Black books". They are almost always cheaply made and in paperback original, covering a range of subjects from Afrocentric history to liberation philosophy to tawdry and seamy accounts, but all targeted at an exclusively African-American audience. The ethnography Sidewalk covers the genre a little, but there are surely better sources.

Slim was a popular author in this genre, publishing close to a dozen books both fiction and non-fiction, but all essentially aggrandizing pimping. Slim began his writing career in the 1960's, after being released from prison for the last time. Here you can read a review and summary of one his autobiographical book.

Slim had the colorful clothes, the distinctive demeanor, and even wore sunglasses in several publicity shots. There he is leaning on an umbrella rather than a cane, however. The cane, the umbrella, and similar items should not be mistaken for mere accessories, for they were used to mete out violence against women (and occasionally male customers or rivals) as violence, both physical and psychological, is sadly core to what a "pimp" does.

Pimps of later generations were affected both by the works of people like Slim and the style of the 1970's Blacksploitation movies such as Shaft, Dolomite, and Superfly. Pimp "Don "Magic" Juan," who clearly aims to be a walking embodiment of every pimp stereotype, said of his youth,

I'd see a pimp, so I'd pattern myself after that. I'd read Iceberg Slim. I'd watch Superfly, with the flashy cars and clothes. I went for all of that. When I came to the game I was 16.

Since the 70's, it seems, many actual pimps have been self-consciously been trying to fit themselves into the mold of early pimps like Slim as well as Blacksploitation heroes. Juan even founded a "Player's Ball" as a debauched "celebration of pimp culture". But not surprisingly, this idea for a player's ball was itself inspired by a movie, 1973's the Mack.

So early pimps have many elements of this pimp lifestyle but not necessarily all the fashion elements we associated. By the 60's people like Iceberg slim are discussing and it's making an impression on a wide black consciousness. This idea of a pimp as a stock character anti-hero was then put into Blacksploitation movies, but of course an exaggerated of the real thing. Indeed, in some cases, notably the Mack, actual pimps participated in their onscreen portraits as advisers and such, ensuring that they'd be portrayed in flattering terms. Later pimps emulated not just earlier pimps, but also took their cues from these pimps in movies and books and, when combining these elements from Blacksploitation movies more generally, we get much of the modern pimp. Things like the Player's Ball, but also portrayals in movies, books, songs, and music videos helped cement one singular national image of "the pimp", often taking the flashiest elements of individual pimps, which were then sometimes reborrowed by actual exploiters of women.

All these tropes were firmly in places by the 1990's as you can see in the documentary American Pimp (which spends almost no time criticizing pimps and presents the whole thing as an enviable lifestyle worth emulating) which is widely available online. Similar documentaries, like Pimps Up, Hoes Down (also widely available online) also show how the stock character of the pimp is now a lived reality for many actual pimps. What's interesting is that a lot of these elements seemed to have only fully coalesced in the 1990's, as rap songs from the 80's often lack some elements and to stray more from the stylistic fashions of Slim. Ice-T early in his career, for instance, tended to dress in largely contemporary styles, just as Slim dressed in mainly (flambuant) contemporary styles of the 1960's and 1970's. However, at some point, the image of the pimp (at least, the African American pimp) became synomous with the image of the pimp in Blacksploitation movies (take a look at the trailer for 1974's Willie Dynomite or Dolemite).

The point seems to be, there was a reality based on flambuant but contemporary fashions in the 1970's and earlier, that was taken into movies and exaggerated, and this movie pimp fashion was then adopted by some actual pimps as a timeless indicator of their status, this has been then retaken into pop culture. I believe this occurred in the 1990's, since I haven't been able to find any of the flashy 1970's Blacksploitation pimp depicted in the 1980's or early 1990's at all (besides rap music as evidence, look at Morgan Freeman playing a pimp in 1987's Street Smart, who is flamboyant in someways, such as his cowboy hat, but not in the same mold as Blacksploitation era pimps as another example). However, without further research, I can't definitively establish the time line.

It's important to realize, however, that there is a tremendous amount of life imitating art, and many actual procurers of women emulate the flashy pimp styles glorified in film.