That depends. It is up to the commander to allow the Soldier to go on leave. Imposition of punishment begins immediately if a later start date is not stipulated during the announcement of punishment. Any repercussions for the Soldier not having to complete the entire extra duty imposed falls on the 1SG and Commander for not informing the BC prior to the punishment phase of the Article 15 proceedings.
Extract of AR 27-10
AR 27-10 – Military Justice – governs Non-judicial punishment – specifically Chapter 3. Imposition of reduction in grade and/or forfeiture of pay has no bearing on whether the Soldier is on leave or not. However, imposition of deprivation of liberty (extra duty, restriction, correctional custody) will be affected by the Soldier being on leave.