Note: While you can do this on an assignment-by-assignment basis I would suggest setting it up as your course default. It would then apply to ALL of your assignments not just one. This KB article only describes setting it up on an assignment basis. You might do this if you want your students to take a quiz at the same time their Student Opinion Surveys are due.
Create your assignment / quiz
Publish the assignment
Go to the grade book tool
Mouse over the header of the assignment you want to change the grade posting policy on
Select the kabob (three dot menu) that appears to the right of the assignment title
Select Grade Posting Policy
Choose "Manually" from the panel that flies out on the right
Students will now see a message in the "Grades" tool telling them the instructor is currently grading the assignment and will release the grades soon.
Post Grades
After you start grading the assignment you will notice an eyeball icon (with a slash) appearing in the header of that assignment in the grade book. This indicates that students are getting grades but cannot yet see their grades. When your finished grading you can then "Post" the grades. This will release the grades so your students all see their grades at the same time. I recommend waiting till all your students have gotten a grade before you post.
Go to your grade book
Mouse over the header of the assignment
Select the Kabob (three dot menu) to the right of the assignment title
Select "Post Grades"
You will be asked if you want to post to everyone or only those that have grades
Select "Post"
