The Planning Board shall refer to the Commission every application for development submitted to the Board for development in historic districts or on historic sites designated on the Zoning Map or identified in any component element of the Master Plan. This referral shall be made when the application for development is deemed complete or is scheduled for a hearing, whichever occurs sooner. The Board shall provide a copy of its agenda to the Commission members as soon as it has been prepared and at the same time that it is mailed to the members of the Board. Failure to refer the application as required shall not invalidate any hearing or proceeding. The Commission may provide its advice, which shall be conveyed through its delegation of one of its members or staff to testify orally at the hearing on the application and to explain any written report which may have been submitted.