My application was submitted May 31st, and conditionally approved on June 21st. However I did not see the email nor check the website till June 27th. The earliest time slot I can reserve for interview was July 10th, but I'd be out of country long before that. Since I depart on July 1st for an international trip, i decided to give it a try for a walk-in interview at the Tucson International Airport. When I walked in, no one except a CBP agent was there. He was cool but not too talkative. He asked who I was and why I was there. I calmly explained my wish to have an earlier interview due to my upcoming trip. He proceeds ask me a couple of question, took finger prints, and I was out there in 2 minutes. A really pleasant experience.