In the November Visa Bulletin, the Department of State (DOS) provides its prognosis on the likely availability and movement of visas for the next few months:

For Family (Worldwide) Categories: F1, expected to advance three to six weeks; F2A, three to six weeks; F2B, one to two weeks; F3, one to two weeks; and F4, up to one month.

For Employment Categories:  EB-1, current; EB-2, current for Worldwide, Mexico, and The Philippines. (For China EB-2 and India EB-2, DOS reports that the current EB-2 cut-off date is approaching the most favorable date previously reached for such applicants; the dates reflect an effort to generate demand based on new filings for adjustment of status at USCIS offices. DOS advises, however, that once the level of demand increases sufficiently, the forward movement may be slowed or stopped, and a retrogression of the cut-offs at some point during the year is possible); EB-3, for Worldwide, expected to advance up to one month; China EB-3, one to three weeks; India EB-3, up to two weeks; Mexico EB-3, up to one month; Philippines EB-3, up to one month; EB-4, current; EB-5, current.