Surrick's ruling exempts the case from provisions of the Speedy Trial Act, which generally calls for criminal trials to begin within 70 days from arraignment.
A federal grand jury returned a 62-count indictment in July charging Brown and four charter school administrators with defrauding three charter schools Brown founded of $6.5 million.
She and her codefendants have pleaded not guilty to all charges.
In documents filed with the court, federal prosecutors said that the criminal investigation was continuing and that "the government anticipates that it may seek the return of a superseding indictment that adds charges against some of the current defendants and potentially other persons not yet charged."
A former Philadelphia School District principal, Brown founded three small K-8 charter schools in Philadelphia: Laboratory, which has campuses in Northern Liberties, Overbrook, and Wynnefield; Ad Prima in Overbrook; and Planet Abacus in Tacony.
In 2005, she also helped create Agora Cyber Charter School, which provides online in-home instruction to students from across the state.
Brown was forced to sever all ties with Agora four years later to settle several civil suits. Now based in Wayne, Agora operates under new leadership.
Contact Martha Woodall at 215-854-2789 or martha.woodall@phillynews.com.