Anytime Maximus. If your just using your D700 for fun and your not making color critical prints I'd say you'll do fine without calibrating. Basically calibrating your camera requires software such as Adobe Camera Raw. This is a program that is used with Lightroom and Photoshop. If you don't use these then you don't have to mess with anything on your camera.
The calibration requires you to adjust your monitor, printer, and camera. The adjustments take place in the software and you don't actually adjust anything in your camera.
What you can mess around with are the different color spaces in your camera(sRGB,AdobeRGB)but I would recommend you just leave it set to the default color space (sRGB, I think).
So just get to know your camera and forget about the calibrating stuff for now. In the future you can buy software like Spyder Pro or Color Munki to calibrate your monitor. But if you stick with sRGB color space you should be OK for now.