Elizabeth 1, 5 x 7 oil
I decided to paint the background a darker tone. Still keeping the color warm, but much less vibrant than the orange. The colors in her face now appear much lighter and vibrant. Her pink blouse no longer fades into the background but becomes and element in the painting.
Elizabeth 2, 5 x 7 oil
So my answer to the question, what comes first the model or the background is both need to be taken into account throughout the paintings progress.