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:

Date time preset in Watermarking

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

Output image stamped with short date time

Date and time preset uses local regional settings on your computer.

To compose your own date time formats see macros  support in Watermarking PRO