I recently had my first ever SSBI last month, and all went quite well. The experience isn't anywhere near as bad as many first-timers think it will be. It's not! Stay calm and carry on! :-)
About the only hiccup I had was that I had answered "Yes" to Question 19 - Foreign Contacts. I listed a resident alien social acquaintance of mine (because I do stay in occasional contact with her). During the course of my interview with the BI, however, both the BI and myself realized that I am not "bound" to my Mexican social acquaintance and shouldn't have really listed her on the SF-86 in the first place. My BI even suggested that I do NOT list the foreign acquaintance in five years and simply answer "No" when my first periodic SSBI comes up. She also said that this question confuses a lot of people and that changes on subsequent SF-86's are fairly common.
So, any quick guidance on how I can mitigate this minor discrepancy in five years? Is this something that can easily be discussed during the periodic Subject interview with the BI, or will I need to write up an explanation? My thinking is that I simply answer "No" to Question 19 when the time comes to resubmit my SF-86 in five years and explain the change in person only if asked.
[For what it's worth, my BI made it politely clear that she wasn't a fan of additional comments and added that most investigators really don't care for them.]