The business may propose a date, but the actual immigration requirements and process must be reviewed for the changed work.
Recheck before relying on earlier preparation
Identify what remains supported and what must be updated. An unchanged calendar date does not establish unchanged eligibility.
Start with whatever takes longest: a credential evaluation if any degree is foreign, then the employer letter revision, then transcripts, then the passport check. A hiring deadline does not establish direct professional support or authorize work, and a generic letter should not substitute for facts the employer has not decided. Discuss with the employer whether the proposed start date can flex if either step takes longer than expected, and avoid resigning from current arrangements in Canada before the visa step is resolved. A Canadian citizen may generally request TN admission at a port of entry, and an employer petition is an alternative with its own processing time; neither shortens document preparation. A period requested in the employer letter should reflect the real engagement rather than a maximum, since an extension is a fresh assessment against the same requirements rather than an automatic renewal.