How to "Set" the date (and time) of a selection of photos.

There is no batch changing tool on Photos to set several photos at once to the same date, like we had in iPhoto. The "Adjust Date & Time" tool is meant to fix a clock error in the camera, to shift the date and time of all photos by the same amount.

I am using an Apple Script to set the date and time of scanned photos to the same date and time, with an increment of a minute between successive photos, so they will remain in the same order when sorting them by the date taken.

See: Script: Batch Change the Date and Time to a Fixed Date

When the photos have been taken at the same location as well and need the same titles and keywords, I am using this script: Script: Lift and Stamp all Metadata from one Photo to All Other Selected Photos

To use the scripts, I arrange the photo in an album in the order I want them to appear, then set the date and the location of the first photo as I want it, then select all photos in the album at once and run the script from the scripts menu.

Launch the Script Editor.app , then open the Preferences for the Script Editor. The General tab of the Preferences has a checkmark to add the Scripts menu to the main menu bar. It will add a cute little icon looking like a parchment scroll, and you can launch your scripts from this menu.

The Help menu in Script editor has a link to the Apple Script Help and an Apple Script user guide.