Backwards from the licence, not forwards from the offer. Admission can be granted for a period of up to three years and is available quickly to a Canadian citizen, so it is rarely the constraint. The state regulator sets the true earliest start date, and the offer letter should be dated to match it.
The slowest regulator sets the calendar
Hypothetical example: Marilou is an occupational therapist whose American start date depends on a state licence she has not yet been granted. Because a Canadian citizen may present at a port of entry or preclearance without a visa, applicants often assume the border is the bottleneck and plan around it. In a licensed profession it almost never is.
Marilou should obtain the state board's current processing estimate in writing, start verification of her Quebec education immediately, and only then ask the employer to set a start date with a realistic margin. Two improvisations tend to appear in the gap and both create problems. Beginning to work remotely for the American group from Quebec raises questions about when the employment started and who was really the employer, and it can contradict the letter she later presents.
Travelling early to observe, then quietly treating patients or supervising staff, is unauthorized work regardless of whether anyone is paid. If the licence slips, the correct response is to reissue the letter with new dates rather than to enter against the old ones.
- USCIS: TN NAFTA Professionals
- U.S. Department of State: USMCA professional workers
- Department of State: 9 FAM 402.17, TN and TD guidance
- eCFR: 8 CFR 214.6, Citizens of Canada or Mexico seeking temporary entry as business persons
- USCIS: Form G-1055, Fee Schedule
- USCIS translation requirement, 8 CFR 103.2(b)(3)