To give the interviewer confidence that you're able to manage your time effectively, be specific about the exact actions that you would take to ensure that the objective is completed. Explain each action briefly by telling the interviewer why you're doing it in terms of what benefit you gain from the action.
"First, I do a quick reading of the document so that way I can get a general gist of the piece. That way I know what to expect in terms of style, pacing, and structure. On this first pass, I'll take any quick notes that come to mind immediately, but I don't pause to do any deep thinking until later.
Then I do a section-by-section reading. I start with the first paragraph and then read the last one to understand what the writer is trying to accomplish. I work backwards from the goal and see if the rest of the writing supports that goal. Next, I..."