The midfielder was signed from Bloemfontein Celtic as a replacement for the departing Reneilwe Letsholonyane who joined SuperSport United.
Buchanan and seven other players were unveiled to the public last week and the 25-year-old was handed the number 10 jersey by the Glamour Boys.
Nkosi, who sported that particular jersey number himself, says that weight of expectation should not be allowed to derail Buchanan.
Although Nkosi followed a similar path back in 2006, joining Chiefs from Celtic, he claims that the circumstances are different.
"One thing for sure that we need to be clear about; we had intentions and different goals between me and him," Nkosi tells snl24.com/kickoff.
"He came from Celtic and I also came from Celtic. Keagan was not the main player at Celtic and I was the main player there so that changes everything in terms of the expectations from the people and also the way you arrive at the club, especial at a club like Kaizer Chiefs.
"I came from Celtic and I was like a big star and people were expecting this and that and they gave me the number 10 based on their opinion and my reputation.
"So it was different dynamic then for Keagan and I think from my side we shouldn’t hype it up too much.
"Let’s allow him to settle because he is still young and he hasn’t played under tremendous pressure and everyone is expecting big things from him but let him grow to the Chiefs system.
"He is good prospect and let him grow and become the star at Chiefs. He is on his way up; he’s not at the level I would say he is a finished product and he can just get on and just deliver. I think we need to look at him that way because it is different dynamics."
"I think he needs to get that out of his head first as Chiefs is a very tricky team to play for," he added.
"The important thing when you arrive there is to forget about the hype and everything and what everyone is saying."
The number 10 jersey has been worn by the likes of the late Shakes Kungoane, Michael Nkambule, Songwe Chalwe and Stanton Fredericks at Chiefs.