[Norm Lenhart]

I meant the actual fusion thing. What I am curious about is the timeframe.

I would assume the core being the highest pressure/temp is the starting point, but considering the sheer mass/size of a star, how fast does the entire ‘star’ become involved in the reaction? is it more a ‘slow burn’ or ‘blinding flash”?

[Telepathic Intruder]

I'm not exactly sure how it works in brown dwarfs fusing deuterium, which is only a tiny fraction of the total hydrogen, but stars only fuse elements in the core. When that's used up, the star dies. The more massive the star, the shorter the lifespan on the order of around mass to the power of -3.5. This is a lengthy topic, however, but the Wiki page should give you a decent overview:

http://en.wikipedia.org/wiki/Stellar_evolution

[Telepathic Intruder]

Actually that’s mass^-2.5, but minor point. For example, a star twice the mass of our sun will last 18% as long, or 1.8 billion years. Half the mass, 5.6 times as long.