Section 7B. Immediately after the right to damages becomes vested, the board of officers who have made a taking under this chapter shall do all things and execute all documents necessary and within their lawful authority for the prompt payment of all damages awarded in the order of taking. In the event that authority to make or approve such payments, or to perform any act necessary thereto, is conferred by law upon any person other than said board of officers, such person shall do all things and execute all documents necessary and within his lawful authority for such prompt payment. Any check for the payment of such damages shall be issued either within sixty days after the right thereto becomes vested, or within fifteen days after demand therefor by any person entitled thereto is made, as said board of officers shall determine, and shall, except as provided in section seven D, be made immediately available to the persons entitled thereto at such time and place as may be designated by said board of officers.