The board of county commissioners of the county, or of the oldest county in case of counties joining, shall cause the persons named for the commission to be notified of their appointment in a notice that shall name all such persons and shall designate the time and place of the first meeting of the commission. The commission, having come together pursuant to such notice, and its members having taken the oath hereinbefore prescribed, shall have full powers to organize and proceed with its business as a deliberative body.