amex is not badam not sure about recently, but as mentioned in another post, B1 is all the time the most easy one, I saw one B1 is 6mth, not sure if it is always 6mth, so sept will not affect your visa valid. the embassy will present you a notice notifying you about which date you should go to embassy if you ask Amex to do it for you, i am thinking maybe the other agencies are the same procedure? and do not know why, heard from friends that with agencies, it is easier, hehe not sure correct or not but it will definatelly help if you get the company sponsorship. anyway, get full prepared and wish you good luck