I dont even know if anybody on here is old enough to answer this, but when did people start saying Michael Jordan was the greatest? I would think around '94, '95 or something, but I dont know.
Some People were writing Jordan off as the greatest even before he won his first NBA title. The majority of people hopped on that band wagon after he won his first 1-2 titles, It was pretty early in his career.
I'd think, as people said, people started calling him the greatest after he won a title or two. I'd think it was solidified (everyone said that) after he won his 4th or 5th.
Like Ballahollic said, he was regarded as the most talented player in NBA history when he first came into the league, and everyone said he was going to be great. It wasn't until that he won those first two titles that everyone started saying that he really is the greatest player in NBA history. By the time he won his 4th and 5th titles, it was solidified like Kmart said, after his 4th title.