If you mean that you put on AADSAS that you planned to take the DAT in August but have subsequently rescheduled, I wouldn't be too worried about informing the schools as they have plenty else to do and will basically hold off reviewing your application until they have DAT scores. You might want to send the admissions office a snail letter updating the test date but that's all I would do. Your application just won't be looked at until they have DAT scores - three weeks after the DAT. Some schools will consider your unofficial scores if you fax or mail it to them and then verify it when they get the official results. It sounds like you're steering towards the late end of the application cycle. Good luck.
