Yes, ownership and source records can be organized while the transaction is pending. Filing readiness depends on the actual capital arrangements and supporting evidence, so a planned exit date is not itself an immigration milestone.
Track each payment condition
List required approvals, closing conditions, holdback releases and distribution steps with their supporting documents. Ask counsel how the proposed investment commitment fits the filing requirements. Avoid a project funding promise that depends on an uncertain buyer payment.
Once the sale closes, add the actual receipts and revised calculations before presenting the source narrative as complete. Preparation can begin well before completion and generally should, since the ownership history is what takes time and it is entirely knowable in advance. Assemble the corporate records, the acquisition documents and the accounts while access to them is straightforward, and identify anything that would be difficult to obtain once the company changes hands.
What cannot be settled beforehand is the amount received, so avoid committing to a figure until the completion statement exists. Track each payment condition separately: what is payable at completion, what is held back and until when, what depends on future performance, and what could reduce any of it. Where a deal is subject to conditions or regulatory approval, treat completion as uncertain in timing rather than fixed, and avoid arrangements elsewhere that assume a particular date.