Their estimations cannot be trusted. For many people, the predicted time passes, and they don't get approved. It's best you create your own timeline here and compare with others.
How are we supposed to know? You didn't tell us what US Consulate the beneficiary will interview in.
Also, there's still the NVC stage. Assuming you sent in all the correct documents, it takes 1.5 months to become "documentarily qualified". Then depending on how backlogged (or not) your consulate is, the wait starts.