As soon as the ownership records are updated and the U.S. plant can be shown to be operating; there is no mandatory waiting period. Preparation of the evidence usually takes several weeks, and USCIS processing follows, with premium processing available for a faster decision.
Let the corporate paperwork lead and the petition follow
The sequence is closing, records, evidence, petition, decision, travel. Filing before the share register reflects the purchase invites a request for evidence or a denial, so the first task after closing is to have the corporate secretary update the ledger and issue certificates. In parallel, the Canadian company can gather Dana's employment history and organizational charts, and the U.S.
plant can pull payroll and customer records. A petition assembled this way can often be filed within a few weeks of closing. USCIS processing then runs according to current times, which vary; premium processing shortens the wait for an additional fee.
Dana should not begin managing the U.S. plant in any capacity that amounts to work until the petition is approved and she has been admitted in L-1 status; business visits to observe and attend meetings are a separate matter that an adviser should confirm. Extensions are filed before the current period expires.
Hypothetical example: Alma directs a Canadian commercial-laundry equipment distributor that buys a U.S. service company. The first calendar should put corporate closing and ledger updates before the petition, then allow time to collect her qualifying foreign-employment evidence and management records.
The share ledger and payroll date settle when the case can be filed. Alma cannot use travel as a substitute for work authorization. Her available L-1A period is capped at seven years, and the qualifying role must include a continuous 12-month period outside the country in the relevant three-year lookback.