Preparation of the corporate and employment evidence typically takes weeks; USCIS adjudication depends on the current backlog unless premium processing is purchased. A Canadian citizen can then apply for admission at the border with the approval notice.
Sequence the evidence so the petition can be filed once
The slowest part of an L-1A case is usually assembling proof that already exists somewhere: a share register that a Boischatel accountant last updated years ago, payroll records that need to be pulled for a full year, a Maine lease that is still in the landlord's file. Start those requests before any lawyer drafts a word. Once filed, the petition waits in the USCIS queue unless the employer pays for premium processing, which produces a decision in a defined number of business days.
After approval, a Canadian citizen presents the notice at a port of entry; a spouse of another nationality may need a consular appointment, which adds its own lead time. Hypothetical example: a Boischatel precast producer wants its director in Maine for a plant expansion opening in the autumn; working back from that date, the ownership documents and payroll should be assembled by early summer. Diarize the three-year initial period and the seven-year ceiling.