IMO, u don't need to take another test today. Most experts suggest that one have a rest and relax on the day before test. And I am completely agree with them. Just enjoy ur day today Do whatever u like if you think that helps you to feel good and concentrated.
On test day actual GMAT quantitative is a little bit easier than that of GmatPrep or Kaplan
So don't worry too much.but Be very careful. Try to read the question thoroughly
Quantitative problems are wordy.
This is my personal opinion. My official Quantitative is 48.
GOOD LUCK!!!. I wish u all the best in ur test! I hope tomorrow the # of of 700+ clubbers will increase by 1 more.