ImageMagick really is a Swiss Army Knife of usefulness …

a more obscure option is exiftool – and documention

• setup an input folder and a destination folder beforehand
• copy photos from phone to input folder
• bonus: decide on separate suffix or initials for each of you

exiftool -progress -d <destination-folder>/%Y%m%d-%H%M%S-<suffix>.%%le "-filename<CreateDate" <input-folder>

    -progress
        verbose and shows an [x/y] progress
    -d <destination-folder>/%Y-%m-%d-%H%M%S-<suffix>.%%le
        renames to YYYY-mm-dd-HHMMSS-sfx.ext format
        and lowercases the extension
    "-filename<CreateDate"
        uses the image creation date (from EXIF metadata) for the above naming scheme