I don't think there is a "correct" way of doing it. The main thing is to understand what you are doing and why - and as long as you understand it, any (sensible) method should be fine.
As Blinkz says, an autopilot will probably cut the corner, and a modern GPS will prompt you to turn at such a time as to cut the corner. And, with both autopilots and GPS being allowed on IR tests now, this might create a good argument for doing it this way - but that's not to suggest that any other way is "wrong".
FFF
----------------