The entire timeline can vary greatly from person to person. Some attorneys who do a few of these a year might estimate the average at about a year. As of 2017, if you do everything correctly, avoid getting a request for evidence, and aren’t from a high-fraud area, the process is taking on average from 5 to 6 months, from start to finish.
After you file the I-129F, you will get notification that the USCIS has received it (NOA1/Notice of Action 1).
Quite likely the most frustrating wait. This is the time between USCIS receipt and approval. You’ll be notified via NOA2.
When your case moves to the National Visa Center.
When your case moves to the local U.S. embassy.
The time after approval until you get the visa in-hand.
For a more detailed description of the process, go here.
Some countries have longer processes that can be brought on by the local embassy workload, conflicts in the area, or other unexpected delays.
The most common delays are brought on by RFEs. The vast majority of these can be avoided if your petition is assembled professionally.
In the past, influxes of USCIS workload have affected overall timelines. This could be brought on by changes in immigration processes or policies.
Petitions that are easy to move through and approve tend to get approved faster.
Events such as these are out of your control can cause unexpected delays.