Just in reference to all the people saying just use first person as dialogue and move to third person afterwoulds.
By doing that, in a way you are just proving that you have a prepared response. The stimulus is supposed to direct your story rather than just be thrown in at the beginning and then ignored the rest of the way. If I they give you a first person stimulus, just sort of cheating it by using it as dialogue or something is probably gonna just make you look less sophisticated off the bat in the eyes of the marker.