I think you're in trouble... Check atlanta.itamaraty.gov.br/en-us/how_to_apply.xml for details. There, they say it takes between 5 and 20 days to "process the visa" (depending on how you do it), vi longer than you have. You can try to go there without an appointment (the shortest wait for an appointment is usually 20 or more days) and see what happens but your chances of getting a visa immediately are practically nil). Good luck!
Yes visa just in the office
Iam not sure ,But i think you can get visa online ...
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