(a) Beginning January 1, 1990, at the time a commission approves a proposal for an incorporation or a reorganization which includes an incorporation, the commission may determine the sphere of influence for the proposed new city. The commission shall determine the sphere of influence for any newly incorporated city within one year of the effective date of incorporation.
(b) Beginning January 1, 2010, at the time when a commission approves a formation or reorganization that includes the formation of a district, the commission may determine the sphere of influence for the proposed new district. The commission shall determine the sphere of influence for any newly formed district within one year of the effective date of formation.