Hi Masami, The early planning part can come at anytime depending on when you learn what course(s) you will be teaching. I have started a year before teaching a course as well as 24 hours when I got assigned a course over the weekend prior to the class starting. Ideally have a month to six weeks to plan out what you are going to do would be great. As for time that will depend on you and how your structure your course. Create a comprehensive outline and then start putting in activities under the objectives and you will start to see how much time you are going to need to completely flesh out the course. Gary