Twin bombs planted at the marathon finish line killed three people and injured 264 on April 15, 2013, in an attack allegedly carried out by Chechen brothers Dzhokhar and Tamerlan Tsarnaev.
The US government accuses 21-year-old Dzhokhar, a naturalised US citizen, of 30 federal charges which could see him sentenced to death if convicted.
Police shot dead his older brother Tamerlan after the attacks.
In documents submitted to the court during the Labor Day holiday weekend, Tsarnaev's lawyers said that holding the trial just 16 months after the attacks provides insufficient time to prepare an adequate defense, and requested a delay until September 2015.
His lawyers said that the current trial start date of November 3 does not leave enough time to adequately test the government's case or to present Tsarnaev's own evidence.
"The sheer scope of the law enforcement investigation... and the massive amount of testimonial, physical, digital and expert evidence that it has generated, have overwhelmed the ability of defense counsel to evaluate and respond to the government's case in the time allotted," they said.
Defense lawyers requested in June that Tsarnaev's trial be moved to Washington, DC.
Prosecutors last month, in their response to that defense motion, insisted it is fully possible to seat a jury untainted by more than a year of wall-to-wall coverage of the case.
