After the structure and the destination account are settled, and early enough that the transfer is complete and evidenced before the file is assembled. Money moved in several tranches needs each one traced. Assembling donor records often takes longer than writing the business plan, and preparation, any consular procedure, government review, and admission remain separate stages without a promised end date.
Start the record requests on day one
Treat the donor's paperwork as the long lead item and open those requests before anything else. Set milestones for the source file, the transfer ledger, and the final review, and check the donor's availability around travel or health that could delay a signature. Confirm current submission instructions for the route being used, leave room for further evidence requests, and revisit the facts if the funding arrangement changes while matters are pending.
Add one further contingency to that schedule: what happens if the donor's circumstances change. A gift depends on a person, and people fall ill, change their minds, face their own financial pressures, or become subject to obligations nobody anticipated. Agree what the plan becomes if the transfer cannot proceed, and avoid committing to anything non-recoverable until the funds have actually moved and the record supporting them is complete.
Hypothetical example: a prospective investor in a property maintenance company holds back on a lease deposit until the transfer has been made and the donor's documentation is in hand, and although the delay is inconvenient, it is considerably less inconvenient than a signed lease with no capital behind it.