Assignment content is not visible to students until after the Available from date and time passes. If you want to keep students from viewing and submitting an assignment until a specific date, set an Available From date.

Depending on their notification settings, students will receive a notification if you publish an assignment even if the availability date has not been met.

When Multiple Grading Periods are enabled in a course, only due dates are validated against closed grading periods.If you manage courses in a time zone other than your local time zone and create or edit a due date for an assignment, the course and local times will be displayed for reference. Beneath the Due Date and Availability date fields, Canvas will display the time zone date and time according to context.For more details, view the Quiz availability dates lesson. In Quizzes, availability dates may affect student submissions. These dates are optional and can be set depending how you want to manage the assignment. These dates are called availability dates. In addition to setting a due date for an assignment, instructors can specify a specific date range when students can submit the assignment.

Open canvas 6 vs sai