The rule of thumb is when you start accurately predicting what your interviewee is going to say, it's probably time to stop. Through these interviews, you'll naturally start to notice patterns. Once you start expecting and predicting what your interviewee is going to say, that means you've interviewed enough people to find and internalize these patterns. 5. Determine which questions you'll ask interviewees. It's time to conduct the interview! After the normal small talk and thank-you's, it's time to jump into your questions. There are several categories of questions you'll want to ask in persona interviews to create a complete persona profile. 20 Questions to Ask in Persona Interviews .