Test Driven Design (TDD) is a technique for ensuring all code has tests and the tests are not showing false positives.

Comment First Design is an alternative technique that aims to capture what is in the designers head during the design of a piece of code.

Delayed in writing comments often means no comments are written at all. If you do have the discipline to go back a few days later then the comments won't be much good

Iterate over these steps:

1. the overview of the interface
2. the methods of the interface
3. implementation class variables
4. implementation methods

Comments are a design tool and help to clarify the designers thinking.