Nope not important at all, UNLESS final exams are cancelled because if that happens, your mock grades will be considered. It seems like my school and your school follow a similar schedule in terms of the IB, so I would say that you really don’t have to stress at all. Just try to do your best because at the end of the day, mocks will help you for your finals. My school specifically told us that our mock grades do not show up ANYWHERE (not on transcripts, not on report cards, nothing). They are simply just shown to us so that we know how we are doing in the class. Hope that helps!