The dates referred to are "cut-off" dates. The cut-off date for an oversubscribed category is the priority date of the first applicant who could not be reached within the numerical limits. Only applicants who have a priority date earlier than the cut-off date may be allotted a number. Immediately that it becomes necessary during the monthly allocation process to retrogress a cut-off date, supplemental requests for numbers will be honored only if the priority date falls within the new cut-off date
If an employer filed an application for labor certification on your behalf, the date it was filed is the "priority date." If a family relative filed a petition on your behalf, the date it was filed is the priority date. You may not file for residency until the priority date for your category is current.
If you are from Mexico and your employer filed a petition (i.e. for labor certification) on your behalf as a skilled worker on April 30, 2001, then your priority date is April 30, 2001 for the category of Employment Based 3d preference, Mexico. Looking at the chart above, you need to find the cut-off date for employment based 3d preference Mexico. If the cut-off date is after your priority date, then you may proceed to file for your status as a lawful permanent resident.
If the cut-of date precedes your priority date, this means that the government has not yet started processing petitions in your category because visas for your category are not yet available.
If your brother from France is an American citizen who filed an I-130 petition on your behalf on July 25, 2002, then July 25, 2002 is your priority date.
Section 201 of the Immigration and Nationality Act ("INA") sets an annual minimum family-sponsored preference limit of 226,000.
First: Unmarried Sons and Daughters of Citizens: (23,400 plus any numbers not required for fourth preference.)
Second: Spouses and Children, and Unmarried Sons and Daughters of Permanent
Residents: (114,200, plus the number (if any) by which the worldwide family preference level exceeds 226,000, and any unused first preference numbers):
A. Spouses and Children: 77% of the overall second preference limitation, of which 75% are exempt from the per-country limit;
B. Unmarried Sons and Daughters (21 years of age or older): 23% of the overall second preference limitation.
Third: Married Sons and Daughters of Citizens: (23,400, plus any numbers not required by first and second preferences).
Fourth: Brothers and Sisters of Adult Citizens: (65,000, plus any numbers not required by first three preferences.)
The worldwide level for annual employment-based preference immigrants is at least 140,000.
First: Priority Workers: (28.6% of the worldwide employment-based preference level, plus any numbers not required for fourth and fifth preferences.)
Second: Members of the Professions Holding Advanced Degrees or Persons of Exceptional Ability: (28.6% of the worldwide employment-based preference
level, plus any numbers not required by first preference.)
Third: Skilled Workers, Professionals, and Other Workers: (28.6% of the worldwide level, plus any numbers not required by first and second preferences, not more than 10,000 of which to "Other Workers".)
Fourth: Certain Special Immigrants: (7.1% of the worldwide level.)
Fifth: Employment Creation: (7.1% of the worldwide level, not less than 3,000 of which reserved for investors in a targeted rural or high-unemployment area, and 3,000 set aside for investors in regional centers by Sec. 610 of P.L. 102-395.)