That requires an individual assessment of what is known, what is missing and what the chosen procedure asks. Do not assume a pending records request excuses inaccurate answers. Keep the employer informed of scheduling uncertainty without disclosing unnecessary private details.
Make readiness a factual decision
Ask counsel to identify what must be resolved before the next filing or travel step. If the missing record is material, plan around obtaining or adequately addressing it rather than a promised retrieval date. Update the chronology when new evidence arrives.
Ask the employer to name a review point rather than an estimate, so there is a moment when the offer is either confirmed or reconsidered. Work backward from the proposed start, but let evidence readiness control the filing or admission attempt. Once the record is settled, a Canadian applicant can decide whether to seek classification at a port of entry or have the employer use Form I-129. TN requires prearranged professional activity, which may be documented by a detailed employment letter or a contract; an executed statement of work is strong evidence but is not invariably a legal precondition. If the employer prefers certainty, filing Form I-129 in advance produces an approval notice before the move, at the cost of processing time or a premium fee.