kjdrga is mostly correct. You submit the I-130 and as soon as you get the first NOA (receipt of your package), you mail that with the 129 to chicago for the K-3. Just went through the process. Most people in my timeframe was 6 months. I was 11 because I had to deal with the consulate in the DR. While other couples were able to complete the process with in 6-8 weeks after the approval of the package, it took me 4 months just to get the paperwork from the consulate to my wife. They use every trick in the book to delay the processing of visas at this consulate
Jerry