Practice in exam scenarios, but also with some light background noise too! I had someone shuffling, asking several questions, humming and mumbling next to me on the DAT and I think it could've helped to practice in a range of settings to train your mind to focus on the exam only.
Also don't burn through all the good reading comp exams too early. It's better to get the technique down now by doing some of the older tests or reading scientific articles frequently. But I think it would've been good to do the heavy reading comp prep closer to the actual DAT.