38 C.F.R. § 21.348
Leave following completion of a period of training or rehabilitation services
(a) Leave following completion of training or rehabilitation services. Leave may not be approved following completion of a period of rehabilitation services described in § 21.340(a).
(b) Postponement of the date of completion of a period of rehabilitation services prohibited. The date of completion of the veteran's program may not be extended for the purpose of allowing the veteran to use leave.