So I have not taken my DAT yet but i'm in somewhat of a similar situation. I am taking my DAT in November and started studying a few weeks ago, so much of my studying will be taking place this fall semester. I will be taking Biochem 1, Mole Cell, microbio, and doing some research in mole cell bio, that being said I understand the anxiety that comes with thinking about studying for the DAT along with upper level bio classes. My advice for your preparation would be to try to take a lighter load if possible (I just took genetics last spring and that class is a beating, however it will definitely help you with that portion of your bio review). From there try and squeeze in as much content review as possible during the semester and constantly review your notes until winter break. Once winter break hits you should have a solid few weeks to go through destroyer and bootcamp. If you finish your content review and want to transition into destroyer in order to really have time to thoroughly go through each question and learn from the solutions that wouldn't be a bad idea. Just keep in mind that its recommended to go through it more than once to really hammer things in. Also, it might be a good idea to expose yourself to some PAT before winter break because that section takes time to get really quick at. All in all, I recommend you to build a foundation before the break so you can focus on practice problems/tests during that time. If you feel that you have a solid foundation as it is maybe an extensive review may not be necessary. These are just suggestions and remember you know yourself best so do what you think is going to help you learn the material most efficiently while allowing you enough time to go through your resources to access your weakness and to work on them. I wish you the best of luck and maybe I can offer you some better advice in the future when I have taken my DAT.