Seeing as how I was a Lakers fan all the way back to when they were in Minneapolis, and went to games, I can tell you that they were instantly popular on the West coast, the minute they moved, because of the people who sat court side. It was a picture of who's who in the movies, TV, and entertainment. It was a ticket that came with exposure to the public, and instantly drew people into their net. It worked very well.
It was that celebrity that filled the stadium, and made them a TV dandy right from the start. It cemented them as a fixture in the NBA.
It was the move to LA by the Lakers that opened up nearly half of the US as a TV audience for their games. Until then, about the furthest West the NBA was popular was St. Louis and Minneapolis. It was an East coast "thing." Out West, it was college basketball almost exclusively.