Judge Dante Terrel on Friday ordered a week-long delay after Guzman, who led a brutal "popular war" to impose communism from 1980 until his capture in 1992, turned his back to the court and gestured at length to the media.
Guzman and other senior Shining Path members shouted:"Long live the Peruvian Communist Party," and "Glory to Marxism, Leninism and Maoism" and "Long live the heroes of the people" with their fists raised to the media.
Police quickly escorted Guzman and the other leaders out of the courtroom.
Guzman, 69, who held sway over thousands of followers, was convicted of treason in 1992 by a hooded military judge at a secret trial and jailed for life.
Guzman's conviction was annulled by Peru's top court last year after the treason conviction was removed from the statute books, and civilian retrials were ordered.
He now faces charges of aggravated terrorism involving a high school academy where prosecutors say teachers recruited rebels, raised money and were linked to Shining Path leaders.
Prosecutors in the trial are seeking a life sentence for Guzman. That would mean he would be able to apply for his freedom in 2027, when he would be 92.
Seventeen other Shining Path members are on trial, including Guzman's long-time lover and the group's number two, Elena Iparraguirre.
Guzman, who called himself Presidente Gonzalo, has confessed to being head of Shining Path, but denies being a terrorist.
"They are accused of terrorism. They are not terrorists," Guzman's lawyer Manuel Fajardo said.