Make sure you save your scene and all objects before you start a Scene Render, and never render a scene to just an animation (unless there is no other choice)! Saving as an image sequence is the safest way of engaging in a long render.
Once you have your scene finalized with all animation, lighting and camera set up, you should perform a Sequence Render with Render > Render Scene or with the keyboard shortcut F10. The Render Status will change slightly to show sequence render time remaining, rather than image time.
At this point, if you have more than one computer at hand, it's a good idea to use them all for this final rendering stage. See Distributed Rendering - An Introduction.