He went to see Ayanda Madulu, later to win renown for his painting of a nude President Jacob Zuma, and picked his brains. "The main thing was to understand how galleries work and how to get my foot in the door," he says.
Back in Cape Town, Witbooi found studio space in the Castle of Good Hope, and went out of his way to catch the attention of Charl Bezuidenhout, owner of Worldart gallery, who was a frequent visitor. It worked, and before long he had a commission.
"Charl gave me advice and set me a challenge to paint something that would fully encapsulate what I was trying to do. I was happy with the piece but not very confident. I gave it to Charl thinking that at least if he put it up in his gallery, I would get some feedback from people who saw it."
That feedback turned out to be immediate. "An hour later he called me to say the painting had sold for R12,000," says Witbooi. "He asked me to do a second one. The same buyer wanted to see if I was someone who could sustain a career. He bought that one too."
That was November 2011. In 2013 Witbooi had his first exhibition at Worldart, and since then the trajectory of his career has headed steadily north. He's even invented a genre, "pap art", to define his approach as a self-taught artist from a part of society with a fairly basic diet.
He has been a resident artist at Greatmore Studio in Woodstock for years; his work is collected nationally and internationally; and two of his paintings have adorned the South African National Gallery.
In his new exhibition - typically, Witbooi was burning the midnight oil when we spoke and unsure how many paintings he would finish in time ("it might be 15, maybe more") - he "explores the colonial genealogy of gardens in South Africa", and links them to "slavery, land dispossession and nationalist propaganda".
There's a lot more I don't really understand in Momo's publicity material. But that's fine. I'm happy to let my mind quietly boggle as I stare at Witbooi's richly complex and wildly colourful paintings, marvelling at his audacious skill and creativity.
"I still have a long way to go," says Witbooi, now 40 and a father of two.
"I'm always trying to get more relevant and to make the language of my art more accessible. The most important thing is for me to be able to say things as a person who lives in the same conditions as anyone else in this so-called democracy."