Neither extreme is safe. Closing outright before a decision risks owning a U.S. business without status to run it; refusing to commit until approval means nothing has been invested. The standard structure is an escrow that releases to the seller on visa issuance.
Write the closing so the commitment is real and the risk is bounded
The application must show funds irrevocably committed, so a purchase agreement with a clause allowing the buyer to walk away if the visa is refused, and money that returns to the buyer, is not yet an investment. The workable approach is an escrow arrangement in which the funds are deposited with an agent and released to the seller when the visa is issued, with the only reversal being visa refusal. Alongside that, the buyer should be far enough into the transaction to show a real enterprise: a signed agreement, a lease assignment in progress, staff retention arrangements, and the licence application filed.
Hypothetical example: an East Hants buyer signs a letter of intent and asks about applying; a letter of intent commits nothing and the application would fail on commitment. Line up the property closing, the escrow deposit, the licensing timeline and the consular appointment on one calendar, with the visa interview scheduled only after the escrow is funded.