On approval of the plan by the state board of education, the initiating unit shall file a copy of such plan with the board of education of each district whose territory is proposed to be included in the proposed joint vocational school district. Within thirty days after receiving such copy, such board of education shall determine whether its district shall become a part of the proposed joint vocational school district. If one or more boards of education decide not to become a part of such proposed district, a revised plan shall be prepared by the initiating unit, and if such revised plan is approved by the state board of education, such initiating unit shall file the revised plan with the board of education of each district whose territory is proposed to be included in the proposed joint vocational school district. Within thirty days thereafter, each such district shall determine whether its district shall become a part of the proposed joint vocational school district.