Review whether the substantive employment, duties or terms changed, and update the factual account.
Distinguish administration from a new role
The effect depends on the actual arrangement and stage. Do not assume either that every change is irrelevant or that a name alone decides the case.
Preparation should begin as soon as the turnaround schedule is confirmed, since port-of-entry processing depends on complete evidence being ready on the day of travel, not assembled after arrival. Tell the employer early that the letter needs to describe actual duties, so the revision happens alongside other onboarding steps rather than at the last moment. Admission is granted for up to three years at a time and can be renewed while the professional employment continues, either at a port of entry with a fresh letter or by petition. If the start date shifts or the employer changes the role, some preparation may need redoing, and agreeing in advance what a change costs is easier than negotiating mid-file. Allow weeks for a registration certificate, a properly drafted employer letter and any restructuring of a self-employment arrangement. TN preparation and the government's actual decision are separate steps, and an expected date is not itself authorization to begin work. An evaluation provider, a licensing board, a foreign university asked to verify a transcript, a professional body confirming standing — each has its own queue and none of them will treat this as urgent.