From watching CSC, it should take 8-10 days from the approval date before the case shows up at NVC. I'd start calling around August 1. The contact information for NVC is on this website:
http://travel.state.gov/visa/immigrants/info/info_3177.html
When they have your case logged into the system, then they give you a case number (you may have to call them back many times before they actually have your case, but eventually they will and they will get you a number. Take that number and go to this website:
https://ceac.state.gov/CEACStatTracker/Status.aspx
Here, you want to make sure Immigration Visa is selected (I know it's a non immigrant, but they handle it as immigrant so you just need to select immigrant or it won't work). Then input your case number, starting with the 3 letters that signify your consulate. do not put in any spaces or dashes, just the 3 letters and following numbers (should be 3 letters and 10 digits). This will tell you when your case is in Transit and will update each step along the way. Also once it's at the consulate, you can contact them as well as checking online.
Hope this helps. Best of luck to you
