Scheduling when a post becomes visible allows you to organize your class better and automates when the post will come out.
You can do this on anything you create in Blackboard; Course content items, Assessments, as well as Participation and Engagements.
note that if you are posting an assessment, the due date has to align with the date the students will have access from
this can be found in the assignment settings [pictured here]➡️
selecting "access until," and selecting a date, the post will become invisible upon that date.