It is likely, and advisable, that you will not wait until the end of your research before starting to write it up. You may be required to produce one or more chapters for assessment part way through your research. The process described above can be used for any individual chapter you are working on. It is important to be prepared to critique and revise your own work several times. Even the early chapters submitted for assessment, and passing that assessment, may need to be revised later on. This is not a failure, but a positive sign of increased experience and skill.