I think you will do fine. I felt the same way before my first test. I also had to rush to class the night of my test (sensei knew my husband and I would be late). Class had already begun and all I had time to do was stretch before testing. I felt like I didn't have enough time to warm up and relax, but in the end, I think it was for the best. It didn't give me more time to think about it. I was a bit nervous when he had us line up and our uke came behind us. I think after the first technique was called, I forgot that I was being graded. I forgot about all the other students who were testing. I forgot about those students who were sitting and watching me test. In the end, I could see that I made a mountain out of a mole hill. At this point, they are more looking at the principals. Are you maintaining your center, are you sinking, do you know the basic movements, etc. They are not looking for perfect technique at this point. Take it easy, relax, get a good nights rest, some good food a bit before you go to class Saturday... and knock em dead.