Have the actual activity and authorization assessed. Calling work preliminary does not automatically place it outside the required permission.
Describe the activity concretely
Do not rely only on a label or an internal schedule.
Identify the latest date the employer could actually accommodate a delayed start without cancelling the position, and avoid non-refundable travel or equipment commitments tied to an assumed entry date. A Canadian citizen applying in person pays the border charge; an employer that prefers a petition pays the filing fee, with premium processing available at additional cost where a start date is tight. Set a realistic timeline for gathering new evidence, confirm the employer still wants to proceed, and keep the applicant's other plans, resignation, travel, housing, flexible until the reviewed strategy is in place. 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. TN admission is granted for a period not exceeding three years and is tied to the employment described, so applying against a schedule that has not settled produces either a refusal or an authorization that no longer matches the work.