I guess courses are meant to start the next day (see MDL-47448) and this is an edge case - but it's possible to break the user report graph (user -> reports -> all logs) if you have attempts and the course hasn't technically started yet. Few people will see that, but it's still not a great look.

Reproduction steps

• Create a course, with the course start date being the next day.
• Enrol some users.
• Create a quiz activity with a true/false question.
• As a student, attempt the quiz.
• As a teacher / admin, view all logs for the student.
  • Observe that the graph at the top of the standard log table is a broken image.
• Change the course start date to the current day.
  • Observe that the graph now works.