..And here's a suggestion to those of you who receive an appointment: Copy the Security Clearance forms to your hard drive before you start filling them out. There is no facility for saving what you've enter unless you do so and the form is 21 pages with every field needing to be completed even if it's N/A. You need to mail one copy and bring the another one with you to I-day, so save a copy of the PDF first, then fill in the blanks.
One advantage. I went through an "Update" for another assignment, and they found an old friend from like 10 years earlier that I totally lost track of. It was nice for us to find each other again. Obviously, this wasn't the air force's purpose for my clearance, but I thanked them for the help anyway. And the initial clearance is definitely going to find anything in your past that they need to find. So as mentioned; be truthful, honest, and don't try and hide anything.