You must get autorisation from your instructor to grade. This is because we want all of our students to pass! If you are not ready to grade, your instructor will tell you what you need to do, to be ready for the next grading in three months time.
If you are told that you can grade, please hand your grading form and fee to your instrustor ASAP. This helps enormously with the huge amount of administration that needs to be done for each grading!