My fiance (wife now!!) submitted the DS-160 and scheduled the interview while it was still "in transit". When she called to book her Medical they advised her to schedule the interview 2 weeks after medical. So she was able to reschedule the interview for the next week to fulfil the two weeks. We didn't need the two weeks because the physician sent the results well within that time. The "welcome letter" didn't come until after she had already done the medical and was preparing for the interview. Hope this helps.