Once I figured out what the heck I was supposed to do, my FBI background check and fingerprinting went pretty smoothly.
I actually got two fingerprint cards sent to me from someone in the Buffalo FBI headquarters for free, after I called asking about the background check process.
Then I had to go to downtown Buffalo (where I live) to get fingerprinted by someone in the sheriff's office. I had to go during certain hours, which were pretty limited. I paid for the fingerprinting in cash. They were very specific about how I could pay. They mailed the fingerprints for me, but left me with the extra fingerprint card, just in case.
After that was done and I sent in my other information to the FBI, I think it only took 3 weeks or so until I got my return letter that I could mail off with my application. It was surprisingly fast, possibly because I live in the same city as an FBI headquarters.
I got my fingerprints done in February of this year (I remember because the first time I tried to go it was President's Day and everyone was working EXCEPT govt employees). It feels like sooo long ago. I also wondered if mine went through quickly because I'd already had an FBI background check in 2009 for a job, so I was already on file. ?
We mailed our complete application in March. The application was received in Buffalo March 31st.
Hope you find this helpful as far as understanding the fingerprinting and background check process!