I would suggest 6 months of operating costs, but HAVE to is a different question? However, in the more than one dozen restaurants that we’ve opened, we’ve never actually done this. It’s REALLY TOUGH to budget this way. I might suggest 90 days of your forecast payroll and rent expense as a minimum to budget for if you can.
In the end, be willing to NOT BE PAID YOURSELF for the same duration, to be safe.