The ordinance provides that the impact fee is due and payable upon the issuance of a structural building permit by the Town of St. John. The issuance of a structural building permit authorizes the applicant to commence construction activities, structural and otherwise. The entire fee is due at said time unless the amount of the fee upon calculation is greater than five thousand dollars ($5,000.00), in which case an installment plan may be requested by the applicant pursuant to the terms of the ordinance. The ordinance also provides that if the fee payer requests, the amount of the impact fee shall be assessed upon the voluntary submission of a development plan or upon the issuance of the structural building permit, whichever is earlier.