No offender may participate in the boot camp program unless such individual voluntarily enrolls by agreeing to be bound by a written contract with the Bureau, which contract shall clearly set forth the obligations, duties, responsibilities and expectations with which such offender must comply. A representative of the Bureau shall also explain to the offender the intended benefits of the program, and the consequences of failing the program. The time served as a boot camp participant shall begin the first day such person is physically within the camp.