The rapper was told by a New York judge he will begin his sentence for attempted criminal possession of a loaded gun on June 8.
The `Always on Time` hitmaker had earlier pleaded guilty in the case and agreed to the sentence - which he later called a "minor setback for a major comeback" on twitter - in December last year.
Rule - real name Jeffrey Atkins - was arrested on July 22 in 2007 after officers found a loaded semi-automatic handgun in the rear door of his car as he left a concert in New York. They had originally pulled him over for speeding.
Judge Justice Richard Carruthers moved the jail sentence start to June rather than this month which gives Rule time to set right an issue he has with tax, and also finish his latest album, `The Renaissance Project`.
His lawyer, Stacey Richman, told the New York Post newspaper: "We want to finish the album, and there`s also a tax issue.
"Somebody, an accountant, had filed an incorrect form, and this is to correct what was done in the past."
Rapper Lil Wayne was also arrested for weapons charges on the same night as Rule, and has since served eight months in a New York prison.