Bytescout Watermarking is capable to add date time stamps to your images with easy. Available date time stamps modes are: Short Date, Short Date and Time, Long Date, Long Date and Time
You can compose your own date time formats using macros in Watermarking PRO
Select date and time format:

See the sample output below (short date format type):

Date and time preset uses local regional settings on your computer.
To compose your own date time formats see macros support in Watermarking PRO