You can pull the date/time from the project you just built and send it to a text file, with the date and time on a single line. Add this to the post-build commands:
for /f "tokens=1,2,3 delims= " %%i in ('dir "$(OUTPUTDIR)$(OUTPUTFILENAME)" ^| find "$(OUTPUTFILENAME)"') do echo %%i %%j %%k > "$(PROJECTDIR)$(PROJECTNAME).txt"