A prepared letter does not guarantee the decision or admission. Consider the actual employment obligations and immigration stage before relying on a departure date.
Coordinate contingencies with the employers
Clarify what happens if the US start changes. Avoid representing an estimated process date as a guaranteed result when making an irreversible personal commitment.
Seasonal work in process industries generates pressure to have paperwork ready months in advance, and that pressure encourages applications built on an outline rather than an offer. A Canadian citizen presenting at a port of entry pays a modest admission charge; an employer filing Form I-129 pays a filing fee and, if it wants a faster decision, a premium processing fee, both set on the USCIS G-1055 schedule. The initial review should produce milestones for credential collection, employer-letter approval, any petition route, travel and permissible start. The passport must be in hand before travel is booked; the letter and credential evidence must match the passport that will actually be presented; the admission record must be checked once entry has happened. If a start date is already fixed, raise that constraint with counsel immediately so the sequence can be planned around it, rather than assuming the letter can be fixed in transit. Admission is granted for a period not exceeding three years and is tied to the employment described, so applying before the structure is settled produces an authorization that does not match the work.