At this time year, it can take longer as this is the time when many students/others start applying for their J-1 visa to work at summer camps in the USA. Once you have applied, you will be booked in to have an interview at the USA Embassy in London and a detailed letter of what you can/cannot bring/do etc, will be with it. Your fingerprints will be taken, so make sure you have no cuts, scratches etc on them - scars are the exception, or else your appointment will be cancelled. The only interview experience I have had with the USA Embassy is that of applying for a J-1 visa to work at a USA summer camp for 2 summers, but only had to attend the Embassy in my first year ('09). As your visa is for a much longer period, the interview will be much longer and some waiting around but it can vary from day to day. Hope you're appointment (you sometimes get to choose the date from a selection of 3, but this may have changed) isn't on a Saturday! I have a friend who recently has returned from spending 18months working in the USA, so I am sure she is more in the know about what happens with the type of visa you are applying for. I'll ask, but I'm sure other posters will be happy to help.