Well, for my it was a long time ago, but normally the IO will ask you for your ID, passport. IO will have on his/her desk all the package that you sent before; at this time you are allow to add any information that you consider might be relevant on your case. Then after this part is done IO starts asking you questions about your case, like dates, names , cities, organizations, etc....most of lawyers advise to answer only what they are asking, not to use many words...................just go to the point. Also of course go well dressed and bring all the papers that you think might need.
Each month, the Visa Office subdivides the annual preference and foreign state limitations specified by the INA into monthly allotments based on totals of documentarily qualified immigrant visa applicants reported at consular posts and CIS Offices, grouped by foreign state chargeability, preference category, and priority date. If there are sufficient numbers in a particular category to satisfy all reported documentarily qualified demand, the category is considered "Current." For example: If the monthly allocation target is 3,000 and there is only demand for 1,000 ap