Entry failures are usually sequencing failures
The business case is not usually the problem. Cost is created by the order in which things are done: a lease signed before the company exists, job offers made before payroll is registered, supply contracts closed before the VAT position is confirmed.
We work back from the planned first day of trading and lock the critical path — company set-up, banking, registrations, premises, people — before anything is committed that cannot be undone cheaply.