At what point did William Shatner truly become Captain James Kirk?

At what point did William Shatner truly become Captain James Kirk?

William Shatner (Author) gives expert video advice on: How did you become the author of ten 'Star Trek' novels?; What inspired you to write 'Star Trek Academy - Collision Course'?; How difficult was it to get approval to write 'Star Trek Academy - Collision Course'? and more...

At a certain point, the actor takes the words, and invests the words with his own personality. So if you played, in this case, Denny Crane, you'd be wonderful in it, but you'd be different from me. So the writers began to see me performing it, and then started to write for what I was doing, and then I would react to what they were writing, and so it became a symbiotic thing, where we fed off each other. And that's how an actor works, I think, with words.