Not in L-1B status. She cannot begin working under the petition until it is approved, and short visits to perform hands-on commissioning are employment, not business-visitor activity.
Approval first; a site visit is not a workaround
Hypothetical example: a Frontenac Islands technician's subsidiary has a municipal start-up scheduled in five weeks and the petition has not been filed. She may not commission the plant in L-1B status until the petition is approved, and treating the trip as a business visit does not solve it, because performing productive work on a U.S. customer's site is employment regardless of who pays.
The company's options are to file immediately with premium processing, to have the technician present the petition at a port of entry as a Canadian citizen where CBP adjudicates it at the time of application, or to send a U.S.-employed colleague to the first start-up with her support from Canada by phone. After-sales warranty service by the Canadian manufacturer under a contract of sale is a narrow exception for visitors, but it does not cover general commissioning work for a U.S. subsidiary and should not be stretched.
The realistic fix is to plan the itinerary from the approval date forward. Hypothetical example: A Frontenac Islands veterinary-diagnostic-equipment firm needs its specialist for a U.S. product launch.
The first review should map the launch date against the employee’s qualifying-year end date, document collection, and adjudication time. Pay records and job descriptions settle whether the required year falls within the look-back period. The company should also plan the handoff of Canadian duties, because an employee cannot begin the U.S.
assignment merely because the launch schedule is fixed.