The Board of Zoning Appeals shall fix a reasonable time for hearing of an appeal or other matter referred to it. Notice of the time, place, and subject of such hearing shall be published once in the official newspaper at least 20 days prior to the date fixed for hearing. A copy of said notice shall be mailed to each party to the appeal and to the Planning Commission. In addition, where an appeal is in regard to a specific property, a notice of such hearing shall be posted in a conspicuous manner on the subject property at least 20 days prior to the hearing.