(a) In any case where a person is sentenced to a period of imprisonment under Code Section 40-6-391 upon conviction for violating subsection (k) of said Code section, it is within the authority and discretion of the sentencing judge in cases involving the first such violation to allow the sentence to be served on weekends by weekend confinement or during the nonworking hours of the defendant. A weekend shall commence and shall end in the discretion of the sentencing judge, and the nonworking hours of the defendant shall be determined in the discretion of the sentencing judge; provided, however, that the judge shall retain plenary control of the defendant at all times during the sentence period. Confinement during the nonworking hours of a defendant during any day may be counted as serving a full day of the sentence.

(b) Any confinement of a person pursuant to a sentence to a period of imprisonment under Code Section 40-6-391 upon conviction for violating subsection (k) of said Code section shall be served in a county jail, provided that for the first such violation such person shall be kept segregated from all offenders other than those confined for violating subsection (k) of Code Section 40-6-391.