Canvas is superior in most ways, but.... My students are used to being able to use calendars in other systems as a way to instantly show a "to do list" for their homework for that day by switching from "view by due date" to "view by date assigned." It is confusing for them to interpret the Canvas calendar, which only shows assignments as "events" that occur on the due date and not earlier. From their point of view, these items are essentially "homework events" that take place earlier.
The best thing would be for them to see all assignments that are "active" on that day, defined as already assigned but not yet due. -- Or seen in a week or month view, these items would actually visually stretch across all those days.