Treat the employer's date as a planning target while the underlying eligibility, evidence, and process are worked through. TN preparation and the actual government decision are separate steps, and an expected date does not itself authorize work.
Identify the next fact that still needs to be confirmed
Ask what remains to be settled before the offer or letter can be finalized, and who is responsible for confirming it. Review current entry procedures before booking travel, and if the employer, the duties, or the assignment changes, ask for a fresh review rather than assuming the original plan still applies. A temporary job offer does not remove the need to separately consider the applicant's immigration history and longer-term plans.
Sequence the work authorization question before irreversible employment steps. First verify the profession and qualification, then obtain any U.S. licence or approval needed to perform the proposed duties, then finalize the employer letter and decide on the procedure. Hypothetical example: a soil scientist is scheduled to begin a remediation assessment soon after a construction permit issues. Her project manager wants a departure date immediately, but the useful record is the permit schedule plus a detailed scope that shows when scientific analysis begins. If a state authorization is still pending, the employer should decide whether the role can lawfully start later rather than presenting an incomplete account. Canadian citizens usually request TN admission during inspection or preclearance; an employer may seek a USCIS decision through Form I-129. Mexican citizens normally need a TN visa before requesting admission. Preserve the temporary dates and review any extension before the original period ends; TN is not available for an owner-controlled enterprise.