(a) A grant of parole shall not be deemed to be operative until a certificate of parole has been delivered to the prisoner.

(b) An effective date of parole shall not be set for a date more than nine months from the date of the hearing. Residence in a community corrections center as part of a parole release plan generally shall not exceed one hundred and twenty days.

(c) When an effective date of parole falls on a Saturday, Sunday, or legal holiday, the Warden of the appropriate institution shall be authorized to release the prisoner on the first working day preceding such date.