The Department of State publishes a monthly Visa Bulletin that tells applicants when their Priority Date is current. Applicants must wait for their Priority Date to become current before they can apply for a Green Card.
First, identify your Preference Category from following list:
Next, identify your country of nationality (If you are claiming chargeability from a country other than China, India, Mexico or Philippines, then you should refer to the first column, labeled "All Chargeability Areas Except Those Listed.") The cell that represents your Preference Category and Country of Nationality will contain either a date or a letter.
If a cell is marked "C" that means that the Priority Date is current in that Category and visa numbers are available. If a cell is marked "U" it means that no visas are available for the rest of the fiscal year (which ends on November 30). If a date appears in the cell, then that date signifies the visa "cut-off" date. Applicants must have a Priority Date that falls before the date listed in the cell in order to qualify to apply for a Green Card.
Please note that if you are applying as the spouse or unmarried childof a U.S. citizen, or if you are applying as the parent of a U.S.citizen who is over the age of 18, then a visa number is immediately available to you and you are not required to wait for a Priority Date to become current.