An applicant who obtains a street or alley closing or a zoning density increase who is required to contribute funds to a housing trust fund pursuant to this part shall proceed in accordance with the following schedule: (1) Not less than 1/2 of the required total contribution shall be made prior to the issuance of a building permit for any of the commercial development; and (2) The balance of the required total contribution shall be made prior to the issuance of a certificate of occupancy for any of the commercial development.