I do not think there is a DAT deadline, you can take it whenever. You need to look at schools deadlines (the ones you will be applying to of course) if you want to get in this cycle. Remember it takes about 2 weeks for your DAT scores to be sent to schools & then any time they need to place it in your file and contact you. I would take the DAT ASAP for this cycle and apply next year if I could not take it a month or two before the school's deadline. Remember that you must wait (is it 60 days or 90 days?? I don't remember) before taking the DAT the 2nd go round. If you hope to get in this cycle, work at it non-stop starting yesterday, I would think you could get in somewhere w/ a respectable ap. If you already started the ap process take the DAT now. I would call the number and ask them, I would think there would be no need for a full on DAT ap again. Hope this helps,
Matt