General help

In 3.9 there is a new feature That allows you to control some content based on a users start date relative to the course start date (https://docs.moodle.org/39/en/Course_relative_dates). Other than looking into that, you may have to consider creating a course "group" Per school week and Place students into groups based on their start week - then you can restrict access to activities based on their group. Lots of set up and maintenance but will give you the results you are looking for.