I. A sentence of imprisonment commences when it is imposed if the defendant is in custody or surrenders into custody at that time. Otherwise, it commences when he becomes actually in custody. All the time actually spent in custody prior to the time he is sentenced shall be credited in the manner set forth in RSA 651-A:23 against the maximum term of imprisonment that is imposed and against any minimum term authorized by RSA 651:2 or 6.
II. If a court determines that the defendant violated the conditions of his probation or conditional discharge but reinstates the probation or discharge, the period between the date of the violation and the date of restoration is not computed as part of the period of probation or discharge.
III. [Repealed.]