Treat the employer's date as a planning objective while eligibility, evidence and the applicable process are still being assessed. TN preparation and the government's decision are separate steps, and an expected start date is not itself authorization to begin work.
Identify the next factual decision
Ask what still needs to be confirmed before the support letter can be finalized, and who controls that missing information. Review current port-of-entry or visa procedures before booking non-refundable travel. If the employer, duties, or client assignment changes, request a fresh assessment rather than assuming the original plan still applies, and remember that a temporary TN offer does not remove the need to consider longer-term intent.
Sequence the case from confirmed facts, not the first workday. Establish Canadian or Mexican citizenship, select the correct profession in Appendix 2 to Annex 16-A of USMCA, verify its individual credential requirement, and finalize evidence of prearranged professional activity for a U.S. or foreign employer. Self-employment is unavailable. A Canadian may apply at a port of entry or have an employer petition through Form I-129; choose the appropriate route before travel commitments. Recheck the letter or contract after any change to duties, worksite, or employer. The recurring mistake is resigning, booking inflexible travel, or beginning services because the company’s schedule labels the date firm.
Hypothetical example: an Ottawa registered nurse is wanted for an American hospital orientation in six weeks, but the final unit assignment and credential records remain unsettled. The nurse should obtain the accurate position description, confirm the profession-specific qualification record, and let the hospital complete its letter before selecting the application route. If the role changes to nonclinical project coordination, reassess the classification rather than rushing under the original timetable.