Only after the petition is prepared, filed and approved, and the manager is admitted; premium processing shortens the USCIS stage but not the preparation. The subsidiary should plan interim coverage rather than assuming a date.
Bridging the vacancy lawfully
The departing general manager's notice period sets the clock, and it is usually shorter than the petition process. The distributor should first decide interim coverage: the parent's Québec staff can support the subsidiary remotely, and the manager may visit as a business visitor for meetings and oversight, but he may not run the day-to-day operation from the United States on that basis, and the line between visiting and working is where companies get into difficulty. In parallel, assemble the records, draft the petition around the functional-manager argument and file with premium processing if the cost is justified.
On approval, as a Canadian citizen he may present at a port of entry and begin work; the family follows on L-2 when ready. If the plan is to hire a local replacement and bring him home, write that duration into the petition so that it is truthful. Any later change, such as merging the subsidiary with another U.S.
entity, alters the qualifying relationship and must be reviewed before he continues.