Much to my surprise, it appears that RT Rider, the preeminent authority of transitarian thought, is the No. 2 place to find the answer. Wow!
Of course I do know something about how long it will take on the train for a rap singer to provoke open revolt among passengers. See here and, to a lesser degree, here. And, once this post has been indexed by Google, I may endear myself to even more wayward Googlers who wish to know how long it will take to train a singer.
This reminds of Richard Brautigan's Trout Fishing in America, which was often mistaken for a book about Trout Fishing in America. I think I'll make that my next book to read after I finish "The Crisis of the Old Order / The Age of Roosevelt, 1919-1933" by Arthur M. Schlesinger Jr.