What is a good process for developing a new course from scratch? If all goes according to plan,
I will be teaching a new course in the next academic year.
Although I do have some experience teaching an existing course
which was previously developed by my colleagues,
this will be my first time preparing and teaching a new course from scratch.

I have done some thinking about my new course.
When we propose a new course,
the university where I work requires us to submit a document
which specifies the name of the course, a brief course description,
the course's learning objectives,
the structure of the course assessment,
topics or key words,
and recommended/suggested readings.

Right now I'm feeling a bit stuck.
How should I go about creating a new course from scratch?
I need to create a lot of material, including:


lecture slides and/or lecture notes
assignments and projects
quizzes and exams


Clearly, it would be a bad idea to wait until
the start of the semester when I am teaching
to create all of this material.
How much should of this material can and should I prepare beforehand?
I strongly recommend backwards design as a way to plan and build a course. The key idea is to start out by clearly laying out for yourself what results (skills, concepts) students in the course should end up with, then figuring out the assessments that will assess this, and then course activities, assignments, etc., that will feed into this. This works very well, in contrast to the "standard" approach of focusing first on content -- making a bunch of readings, slides, etc. -- and then asking later what sort of tests one can make, which invariably leads to the realization that the assessment gets at peculiarities of that particular content rather than the goals you really wanted. With backwards design, things make much more sense. There are a lot of good references on backwards design (just google it), e.g. this.