In Canvas, it is not enough just to click on the eye in Speedgrader to hide the assessments for the students until everything is ready. The setting required to ensure that the assessments are kept hidden until the desired publication date is so-called. Policy for review publication. You make the setting first in Grades in the Canvas menu and then you can assess in Speedgrader.
Instructions on the procedure can be found on our Canvas course "Canvas at University West"