Exam Krackers 1001 Orgo is a must have. It is very close to the type of questions you will receive on the actual DAT. The general chemistry version of the 1001 series will be helpful, too, but it is a little more detailed than it needs to be. Note, that these two books are structured in such a way that the difficulty of each question increases as you proceed through each section's topic-questions--don't wory about finishing the whole thing, but the more the better. Remember to study smart, and by getting an early start you are doing just that. Since the DAT is timed you will not have time to answer the complicated multiple-calculation questions. The DAT is strongly a test of knowledge and basic understanding and straight-forward application of that knowledge. For G-chem, know concepts, trends, periodic properties, what defines certain things [like a strong or weak base]. For organic, know brand name reactions, key reagents, and trends. Even though Exam Krackers may have complicated questions that would take up too much precious DAT time, MAKE SURE to pay attention to what the answer is telling you. Look for generalizations, tends, concepts--anything you can, such that once you read the question an idea will pop up before you even glance at the answers. Now is a good time to start studying for the DAT for the new cycle. Do question after question after question---learn by doing. I highly recommend Exam Krackers as a supplement to the Kaplan Blue book, class texts, or whatever your primary study source is.
-Good luck
-Richard