Section 17. If at the time appointed for such sale the executor, administrator, guardian or conservator considers it for the interest of all persons concerned that the sale should be postponed, he may adjourn it for not more than fourteen days, and notice of such adjournment shall be given by a public declaration at the time and place first appointed for the sale. If the adjournment is for more than one day, further notice of the sale shall be given by posting or publishing, as time and circumstances may admit.