When I asked that to the teacher, he answered me that quizzes only cover what hasn't been tested yet.
The goal is for us to have a "checkpoint" to realize if we are falling behind. Not to actually grade us.
But obviously, general concepts are to be known (like, you need to understand the beginning of the course to understand the rest). But no question will be directed specifically on the material of first lectures.
So focus on the last 2 lectures :)
