There is no set time period for a case to be tried. However your nephew or his attorney can file for a statutory speedy trial demand as well as a constitutional speedy trial demand. They have the possibility of resulting in the case being dismissed. I would encourage you to talk with his attorney about these options if his case is not reached this month.
Wow. It sounds like he is dealing with some of the issues that have been plaguing the Griffin Judicial Circuit in Georgia. Unfortunately Georgia does not have a speedy trial act, like the one in Federal Court, that mandates his case be tried in a certain amount of time. Had his original trial attorney filed a "Demand for Speedy Trial" then his case would have moved forward to trial or it would have been dismissed. However, it is too late for such a "Demand" to be filed now. Now his case must be tried in accordance with the Constitutional Speedy Trial provisions which do not create a definite time limit for his trial to take place. However, if a court finds that his right to a constitutional speedy trial has been violated, it can dismiss the case. These circumstances are rare. Good luck!