But all of this parameters are not absolute. There are a lot of factor that affect your rendering result. For example, how big your window opening, what kind/color of material you are going to use, how many lights you place inside of your room, etc. All of those things will affect the result and your rendering speed. You have to be open for trial and error. A bit troublesome, I know. But the result will be worth all the trouble.
At the end of the tutorial, the rendering result may seem a little bit over bright. It's because we haven't place the material yet (we're going to discuss this on the next tutorial). So if you want, you can use the sketchup default material. It's compatible enough (with the exception with the opacity material) for Vray.
Have a nice day!!