If you view the photo with the software that came with your camera, View NX, there is a box you can open marked camera settings that has the date and the time the photo was created. If you have View NX2 there is a column marked metadata that shows the date and time the photo was created.
What software do you use to view your photos and what computer do you use, Mac or Windows?
If you are using the Windows Operating System, in Windows Explorer you can right mouse click on the image, select the "Properties" option. In the 'Properties" pop-up window, select the "Summary" tab and click on the "Advance >>" button.
Most picture viewer programs and editing programs let you see the 'Properties' of the image. And the "Date Taken" is one of the standardized fields within the EXIF meta data.
There are even specialize programs that display more of the EXIF data.
You may need to use the "Help" menu bar option or the "F1" key to open the Help file for your program and within that file you should be able to search for "Meta" or "Date" and find more information.
Many people have their files automatically renamed when they transfer them to their PC. I use a simple program called 'DMove' which is on my site (URL in signature). I get filenames like 20120108_12081532_D5000.jpg There are many many other options. I'm sure others will add replies with their favorites.