Do not assume that arrangement is authorized merely because the company is Canadian.
Describe the actual U.S. activity
Review the work, employer and current permission before starting. A pending offer or future application does not authorize present U.S. work.
A Canadian citizen can apply at a port of entry the day the file is complete and, if admitted, begin work immediately, so the timeline is set by how quickly the supervising professional's letter and credentials are assembled. Build a sequence from the employer's final letter, credential readiness, any licence issue, the intended request or filing method, inspection or adjudication outcome, and the individual's actual admission record. The practical sequence is to settle the engagement terms, make the corporation’s support letter consistent with the client evidence, assemble the credential and experience records, and then present the application. For a Canadian citizen, coordinate either a port-of-entry TN request before work begins or the employer’s petition and resulting authorization; Canadian permanent residence alone is insufficient. The safer sequence keeps the Canadian licence current and the Canadian job in place until the state credential issues, then moves quickly, because the immigration step itself is measured in a day.