Which chart applies to I-485 filing each month, and every month on record
The bulletin publishes two charts. Final Action Dates govern when a green card can actually be issued; Dates for Filing govern when an I-485 may be submitted, and normally sit several months earlier.
Dates for Filing is not automatically in force. USCIS announces each month which chart it will accept, usually within a week of the bulletin. In a month when it applies, filing early also means work authorization and advance parole, and the option to change employers under AC21.
USCIS decides using three inputs: visas remaining for the fiscal year, the documentarily-qualified applicants State is holding, and its own pending I-485 inventory. Employment-based categories sitting on Final Action Dates is itself a demand signal — known applicants already suffice to exhaust the year's supply.
Source: USCIS "Adjustment of Status Filing Charts from the Visa Bulletin" and its archive, checked automatically each day.
