Non-conforming use rights cannot arise by the mere filing of a notice of intent to build, an application for building permits, or an application for required state permits and approvals. Such rights arise when substantial construction of structures, or development of infrastructure improvements for town approved subdivisions, began prior to adoption or amendment of this Ordinance. Such construction must be legal at the time it is commenced and the owner must be in possession of and in compliance with all validly issued permits. In the case of pending applications, vesting occurs when the substantive review process on an application has commenced. Substantive review occurs when a completed application demonstrating compliance with all Ordinance requirements has been submitted and reviewed by the Planning Board.