Thank you so much for the useful info. I wonder if we submit the timeline and family tree in the interview, they will approve the visa faster. In your case, it took 6 months. That was so long. In my case, they already delayed my fiancé 7 months because USCIS lost the second page of my petition. I am thinking about writing a letter to the white house next month to beg him to ask them expedite my petition. I am not sure what the outcome would be. It is very unfair that they made a mistake and we suffer.