PreviousDate

PreviousDate[gran] gives the previously occurring date of the specified granularity type gran.

PreviousDate[daytype] gives the previous day corresponding to the specified daytype.

PreviousDate[date,gran] gives the previous date of the given granularity relative to the specified date.

Examples

PreviousDate["Month"]
(* DateObject[...] *)

PreviousDate[Friday]
(* DateObject for the previous Friday *)

Please visit the official Wolfram Language Reference for more details.