Before the purchase is structured. Ownership percentages, voting rights and the manager's authority are all decided at closing, and they are the documents the control question is answered from. Changing them afterwards means renegotiating with people who have no reason to agree.
Structure first, close second
The sequence that causes trouble is buying the business on standard terms, moving the family, and then asking how the arrangement should be described. By that point the governing documents say what they say and a manager has been hired on terms that may not fit. Instead, decide the operating intention first, take it to counsel, design the structure around it, and close on documents that reflect it.
This adds weeks at the front of a transaction and removes a category of problem that is otherwise extremely difficult to fix. It also gives the seller a clear picture, which tends to make the closing itself smoother rather than harder. Sellers rarely object once the reason is explained to them plainly.
Hypothetical example: Noelle wants to launch a U.S. mobile diagnostic-imaging service for farm animals before a trade-show season. A timing review should order the business steps so that premises, equipment commitments, licensing questions and the funds trail support one another.
Signed commercial commitments and paid invoices may show that capital is exposed to business risk, while a tentative idea cannot. The business plan should tie hiring and revenue assumptions to a realistic opening date. Delays arise when an applicant applies before the business is sufficiently committed, or commits funds without contractual protections appropriate to a refusal.