Why should you do the beginner one for 3 months....?? If the science is there for this to be beneficial, couldn't any adult start this?
There isn't a clear line between "Beginner" and "Advanced" -- binaural beats affect everybody differently. Some people who try "Advanced" right away report headaches and nightmares, whereas others can jump right in without any problems. It's entirely up to you, I tend to be a bit more on the careful/paranoid side of things. ;)
Nate