I am behind in my study, advice?

I am very behind in my study. I am finding myself having to reteach myself things from earlier in the term in order to continue learning. I have 4 classes I need to study for and 8 full days to do it in. Is it too late? I started study at 8.a.m today and worked through until 5p.m. If I do this for the whole 8 days, do you think this will be suffice?