I didn't take Trump seriously at first, but around this time last year it sunk in that he was serious and a contender. I think the MSM's view of him transitioned from thinking him a loathsome clown to a loathsome serious player happened somewhere around March this year. By that they had already given Trump millions of dollars of the best advertising he ever got, for free.
To this day I don't think the MSM realize how skillfully Trump played their arrogance, contempt, hatred, and lack of self-control. Or even that he did.