Considerable, if the history has to change. Where the conclusion is that a period of genuine employment is required before filing, that period has to actually elapse, and no amount of preparation shortens it.
A year is a year, so find out early whether you need one
This is the type of obstacle that punishes late discovery more than almost any other. If the answer is that the qualifying year is not there and has to be created, the business is looking at a wait measured in months at best, plus the payroll and tax changes that go with it. Establish the position now, even if the transfer is a plan for next year rather than this one. The investigation costs little, the documents are already in the accountant's hands, and the answer either removes a worry or gives the company enough notice to arrange things properly. Deciding the American start date first and investigating afterwards is the sequence that produces cancelled plans.
Hypothetical example: Beatriz manages a salvage-equipment company and is promised a U.S. leadership role at the opening of a new depot. An opening assessment builds a calendar around the company's operational launch, the employee's qualifying-year evidence, and the petition process. Board minutes, lease dates, hiring plans, and payroll records determine which date is achievable. Do not make the American start date the only planning fact. A timing failure occurs when the manager is needed to establish the operation before the paperwork explains who will carry out the subordinate work. If the evidence needs a longer period, rescheduling the launch or using a different interim structure may be the honest business solution.