If such improvement is on the "immediate payment plan" the city clerk shall issue local improvement fund warrants in payment of the cost and expense of the work and it shall be the duty of the city treasurer of the city of Aberdeen to call in and pay said warrants in their numerical order, whenever it shall have sufficient funds on hand to the credit of such particular fund and shall likewise call bonds issued by the officers of the city of Aberdeen when the improvement is being made on the "bond installment plan."