Tenn. Code § 13-7-303
Before adopting the regional ordinance covering territory outside the municipality and which is not then zoned by the county, the county mayor shall be given at least six (6) months' notice of the interest and intent of the municipality to adopt such ordinance. A letter signed jointly by the mayor of such municipality and the chair of the regional planning commission and delivered to the county mayor by registered or certified mail shall be considered sufficient notice. Upon preparation of the zoning plan by the regional planning commission and certification of same to the chief legislative body of the municipality, the chief legislative body shall hold a public hearing thereon, at least twenty-one (21) calendar days' notice of the time and place of which shall be published in the official municipal journal or in a newspaper of general circulation in the affected region.
T.C.A. § 13-7-303