(a)
(1) Time served for a sentence shall be deemed to begin on the day sentence is imposed, not on the day a prisoner is received by the Division of Correction.
(2) Time served shall continue only during the time in which an individual is actually confined in a county jail or other local place of lawful confinement or while under the custody and supervision of the division.
(3) Once sentenced to the division, the division shall retain legal custody of the inmate for the duration of the original sentence.
(b) The sentencing judge shall direct, when he or she imposes sentence, that time already served by the defendant in jail or other place of detention shall be credited against the sentence.