It won't be too quick, if my experience is any indicator. I just renewed and it took exactly one month from application to approval. However, I was pleasantly surprised that I did not have to interview for the renewal despite moving across the country during that time, as well as having entered a European passport in addition to my US passport (that EU passport having not been on the old account because I didn't have a valid one at the time). My wife and daughter are both in process now. I assume my daughter won't need an interview since she's 6. It'd be kind of funny if my wife had to go.