A business date can be recorded, but it does not resolve eligibility or authorize work.
Identify the dependency for the employer
Explain which facts need confirmation and review before the proposed start can be relied upon. Avoid using an incomplete letter simply to meet a commercial deadline.
The two long items usually sit outside the employer's control: a provincial regulator or registrar issuing a letter of standing, and a credential evaluation for a degree earned outside Canada or the United States. The transcript request and the employer's rewritten letter are the slow items; a college may take weeks to issue official transcripts, and a distributor's human resources team may need time to name a supervising engineer and revise a title. A Canadian citizen may request TN admission at an eligible port of entry or preclearance location, or a prospective employer may file Form I-129, but neither option converts incomplete licensing or certification into permission to practise. The usual failure is a slow start followed by a rushed choice: weeks spent waiting for an employer to confirm something informally, then a single week in which documents, a filing decision and travel all have to happen at once.