Start assembling the year-abroad and ownership evidence as soon as the deal is likely, because the petition can only be filed once the qualifying relationship actually exists and the U.S. entity is operating. Processing time then runs from filing, with premium processing available.
The closing date starts the clock; it does not finish it
Until the purchase closes, the Canadian company and the U.S. target are unrelated and no petition can be filed. Hypothetical example: an East Hants freight consolidator signs a purchase agreement in spring with closing in late summer and wants its manager in place at closing. The realistic sequence is to gather payroll records, share registers and the manager's duty description before closing, file the petition immediately after the ownership transfers and the U.S. company is confirmed operating, and use premium processing if the business cannot wait. In the interim, the manager can visit the U.S. site for meetings as a business visitor but cannot run it. If the acquisition instead creates a brand-new U.S. entity rather than buying an operating one, the new-office rules apply with a one-year initial approval and their own evidence. Build the manager's start date around the approval, not around the closing party.
Hypothetical example: an East Hants mobile-crane maintenance company schedules a U.S. acquisition for Friday and expects the incoming manager to supervise work on Monday. The first review should mark the closing proof, corporate records, payroll year, petition filing, and approval as separate gates. The purchase agreement can settle ownership, but it cannot authorize employment. If the business needs operational leadership immediately, it must arrange lawful interim coverage rather than treat a signed deal as permission for the transferee to work.