There is no universal rule. Committing to premises can help show capital genuinely at risk and readiness to operate, while an unconditional long lease creates liability before any decision is made. Conflicting obligations and revocation clauses need fact-specific legal review, and no processing time or outcome can be promised.
Set milestones instead of a single signing date
Useful milestones: guarantee terms settled, funds traced and transferred, premises secured on terms you can live with, business plan complete, packet reviewed, appointment attended. Prelaunch readiness with credible commitments can support a case; first sales are not universally required. Also remember the visa's validity period is not the same as the authorized stay on the I-94, and plan to depart when status ends.
Sensible risk management usually means starting with the expenditures that have independent value if the plan changes, keeping the escrow question under professional advice, and not signing multi-year commitments that only make sense if the visa issues. The interview should be scheduled once the equipment is bought or escrowed, the lease signed and the ownership documents finalized, because the officer assesses the enterprise as it exists on the interview date. The usual middle path is a signed agreement with funds in escrow released on visa issuance, then closing immediately after.