(b) Any period of confinement included in a sentence of a court-martial begins to run from the date the sentence is adjudged by the court-martial but any period of time prior to execution of sentence shall be excluded in computing the service of the term of confinement. Regulations prescribed by the governor may provide that sentences of confinement may not be executed until approved by the designated officers.
(c) All other sentences of court-martial are effective on the date ordered executed.