Advance Import General Manifest filing: commencement deferred; software changes and stakeholder training required before implementation. Advance Import General Manifest (IGM) filing under the Customs Act is to be implemented pursuant to prior Board instructions, with the commencement of the new IGM regime deferred to a later notified date. The department's systems unit must make software changes, prepare procedural guidance, and ensure ICES systems managers provide stakeholder training before implementation.