Case Forwarded to National Visa Center
When the USCIS Service Center send you the NOA2, it may say that your petition is approved or denied and you may be told how to appeal and/or motion to reopen or reconsider and revoke. But when luckily it is approved, your case will be sent to the NVC or National Visa Center.
The NVC will run a security check on your fiance before they send the case to the US Embassy in Manila or wherever your alien fiance may be. The best thing to do again is to prepare all the requirements needed for the interview of your alien fiance. In our case, after my petitioner got the NOA2, it took a total of 23 days before I got a letter from the US Embassy Manila saying that I am eligible to be scheduled for an interview.
You may call the NVC hotline number 603 334 0700 if you want to know that they have received your case from USCIS. You can also call them about your case number so that your alien fiance can already start with the medical exam. To know more about NVC, check their website here.