Cases in Dallas County often take a long time to resolve, particularly if the case is a felony. Unlike federal court the State receives cases filed by law enforcement agencies throughout the county that they have had no contact with until it is filed. It can be 4-6 weeks after arrest before a felony case is heard by the grand jury and in some cases involving drugs it can take much longer as they wait for a lab report on the drugs to be completed. The grand jury may hear the case and decide that there is enough evidence to return a "True Bill" of indictment but when the Prosecutor reviews the case they may determine that more investigation needs to be done. Some of these things might include speaking to witnesses, verifying collected evidence, getting photos printed, etc.
During this time often your case will be "passed for announcement" a few times to give the defense and the State a chance to investigate the case and see if the case can be resolved without a trial. It is up to the individual judge whether you will be required to appear in court for "announcement" settings. In most felony courts you will have to appear but in most misdemeanor courts you will not.
If the case is eventually set for a trial, it may be reset several times. Most courts set multiple cases for trial on each day. Because it is so difficult to have everyone available and ready for trial, having several cases to choose from will usually ensure that someone goes to trial.Older cases and cases where the person has been incarcerated will usually be given priority