There is created a metropolitan area planning and development commission in each area of this state having a population of more than 1,000,000 according to the United States decennial census of 1970 or any future such census. The chairman of the county commission of the most populous county in an area so having a population of more than 1,000,000 shall, within ten days after July 1, 1971, or within 30 days after the publication of the first United States decennial census which reports that an area has a population of more than 1,000,000, as the case may be, activate the commission to serve that area by convening a meeting of the members provided for by paragraphs (1) through (4) of subsection (a) of Code Section 50-8-84.