Before any money moves. The path of funds is evidenced most easily while transfers are being made, and a donor's cooperation is easiest to secure before they have parted with the money rather than afterwards.
Document the money as it travels
Every transfer creates a record somewhere, and those records are simple to obtain in the weeks after they are generated and progressively harder as time passes, especially across institutions in different countries. Decide the route first, tell the banks what you are doing, and collect statements at each step as it happens. On the donor side, have the conversation about disclosure before the gift is made, because a donor who has already transferred funds has less reason to spend a week gathering decade-old paperwork. If the plan involves selling an asset to raise capital, keep the sale documentation complete from the outset. None of this is difficult work, but almost all of it becomes difficult when it is left until the file is being assembled.
Hypothetical example: Zahra, a commercial-kitchen installer, believes an approved petition alone gives her a date for permanent residence. Her calendar should separate petition adjudication from visa availability, consular processing or adjustment, the start of two-year conditional residence and the later I-829 filing window. Project schedules and job evidence belong beside the lawful-source and transfer chronology because the immigration stages do not eliminate the employment requirement. She should retain records after admission rather than treating the petition approval as the finish line. No adviser can derive a residence date from approval alone when visa-number availability and government processing remain separate steps.