If you mean truly born as in no point of going back, then it is choice A and that is fact.

Here is a great video for you. Take a look! (Spoilers)

^ That.

I'd have to say when he first found out he had cancer.

When he was laughing like a maniac in the Crawl space. That was the death of Walter White.

His pose is exactly the same as the end of Season 5, which is the death of Heisenberg.

Since the series has been over for almost a month, time to expand my choice. I feel like Walter White died in the crawl space and became Heisenberg. From the end of season 4 up to the near end of season 5, he was Heisenberg.

I feel that in 514, "Ozymandias", the moment that Jack Welker killed Hank, that's when Heisenberg died and Walt was reborn.

Now, flash forward to New Hampshire in 515, "Granite State". Walt is alone in that bar and sees Elliot and Gretchen on Charlie Rose. Again, I feel that the moment they say Walt had nothing to do with Gray Matter, Heisenberg came back.

Finally, in 516, "Felina", Heisenberg tied up all loose ends, freed Jesse, and died a hero.

So here is my Heisenberg timeline:

Walter White: 101 to 411
Heisenberg: 412 to the start of 514
Walter White: 514 and 515
Heisenberg: 516

See, I tend to think that in his final moments we saw a synthesis. Both personas are finally recognized as being a part of the same person; he's shattered the barriers entirely and has accepted the role he played in this world. There is no Heisenberg, Walter White as he was prior is no more, he has lived his life and this is the end result- this is how it was and always was to be. His final moments staring at the lab are Walt's love of chemistry and Heisenberg's pride of his sky blue legacy.


Just a thought, anyway.