Under the Speedy Trial Act, 18 USC § 3161 et seq, a case is supposed to proceed to trial within 70 days of arraignment on an indictment or information. Some felony cases do resolve very quickly, within a month or two from the first appearance.
Most felony cases, however, take much longer. The average felony case in the District of Oregon takes one year from the arraignment to sentencing. Complicated conspiracy cases or fraud cases can often take much longer. Delays can come from the need to review discovery, interview witnesses, bring and argue motions, negotiate plea agreements, and prepare for trial.
The public defender will discuss the timing of the case with the defendant, and will explain why any delays or continuances are necessary.