Ryan Routh's trial will begin Sept. 8 instead of the previously scheduled Feb. 10, 2025 start date, U.S. District Judge Aileen Cannon said in an order released on Monday.
Routh, 58, a Hawaii resident, has pleaded not guilty.
Routh's attorneys had asked the judge to delay the trial until no earlier than next December, saying they needed more time to review the evidence against him and decide whether to mount an insanity defense.
Routh owned 17 cellphones and numerous other electronic devices, and there are hundreds of hours of police body camera and surveillance videos that have been provided to the defense, Routh's attorneys argued during a hearing two weeks ago in Fort Pierce, Florida.
In her order, Cannon said she wanted to err on the side of providing more time given the seriousness of the allegations, but that starting the trial no earlier than December would be an excessive amount. A September trial date didn't amount to an "unreasonable delay," she said.
The judge said that any insanity defense or any request related to Routh's mental competency must be made by early February. Any visit to the scene of the assassination attempt must be made by the end of February.
Prosecutors say Routh methodically plotted to kill Trump for weeks before aiming a rifle through the shrubbery as Trump played golf on Sept. 15, 2024 at his West Palm Beach country club. Before Trump came into view, Routh was spotted by a Secret Service agent. Routh allegedly aimed his rifle at the agent, who opened fire, causing Routh to drop his weapon and flee without firing a shot. Prosecutors say he left behind a note describing his intentions.
He was arrested a short time later driving on a nearby interstate.
Routh's charge of attempted assassination of a major presidential candidate carries a potential life sentence in the event of a conviction. Other charges include assaulting a federal officer and three firearms counts. He is being held without bail at the federal jail in Miami.
Routh's arrest came two months after Trump was shot and wounded in the ear in an assassination attempt during a campaign rally in Pennsylvania. The Secret Service acknowledged failings leading up to that shooting but has said security worked as it should have to thwart the potential Florida attack.
The Associated Press contributed to this report.