File once the qualifying year is documented, the specialized-knowledge evidence is written and the client contract has been reviewed, and allow time for a request for further evidence. Client-site petitions attract questions more often than in-house ones, so the schedule should assume at least one round of additional evidence.
Sequence the contract before the petition
The order that works is: settle the commercial contract with the client so it describes the company's deliverable, then write the specialized-knowledge case around the employee's role in delivering it, then file. Reversing that order produces a petition that describes one arrangement and a contract that describes another, and the inconsistency is what a reviewer notices first. Give the client a realistic date and explain that the employee cannot begin US work before the classification exists; a short visit for permissible business activity is not a substitute for starting the deployment.
If the timeline is genuinely tight, consider whether the first phase of work can be performed from Canada, since remote delivery from Ontario raises none of these questions and buys the file the time it needs. Hypothetical example: a maritime-navigation software firm promises a specialist for a US harbour deployment beginning in four months. The calendar must include the qualifying-employment check, client contract, internal training records, petition preparation, and the worker's existing status time.
A first review should expose whether the assignment consumes too much of the five-year maximum. The recurring problem is treating a client deadline as proof of eligibility, then discovering late that the company cannot document control at the site or the employee's distinct knowledge.