The court, before committing a child as delinquent to a residential institution, shall first temporarily commit such child to the Youth Services Administration for a period not to exceed forty-five days for evaluation, and the Youth Services Administration shall make a recommendation to the court prior to final commitment; Provided, however, That the committing judge may waive such temporary commitment in cases where the child concerned has previously been evaluated through temporary commitment by the Youth Services Administration and such evaluation is available to the court and the evaluation information is current and relevant.