I'd just like to point out that "roughly planned out" could EASILY just look like this.
Episode 1: Anakins a child, meets obi-war at some point and joins jedi order
Episode 2: Kids a young adult, young jedi, struggles with jedi order, clone wars start, palpatine starts to take over
Episode 3: Clone wars in full force, Anakin is full jedi and starts feeling seduced by the dark side, Palpatine makes his move, Obi-Wan and Anakin fight.
That's it. That's roughly planned out, and it's very possible that he may have had that since the begining.