The DMV should provide you with the chemical test results before the hearing date. If they don't have the results they will likely grant themselves a continuance. If they only get the results to you the day of the hearing you should be able to get a continuance. Good luck.
Of course, every DUI case is different and you should consult an experienced DUI defense attorney in your area with questions regarding your specific case. It is always in your best interest to have a good DUI attorney represent you when you have been arrested for a DUI.
The DMV will not have a hearing until the tests come in. An attorney is necessary to take proactive steps with your DUI with the court and DMV . This is something you want to tackle yourself.