Hey Zimmer,
It depends on what classes you taken previously.. I'm a senior, my last gen chem was 2.5 yrs ago, while ochem was 1.5 yrs ago. It took me about 2 weeks to review and recently took my dat today. I feel pretty ok with my results knowing that I didn't study as much. Bio question is sort of random, but make sure you study that part too. I ended up not studying for bio and got just the average 18. Either way, make sure if you're not ready, then give yourself enough time.
I felt 2 weeks are just like speed-cramming. I was cramming the entire first week, but ended up getting sick on the 2nd week. If you want to get a good score, do tons of practice and make sure you know everything cold. You don't have time to think during this test, it must already pre-programmed ahead of time. If you can postpone it, please do until you're ready.