Two common answers are
- It depends
- 6 month into your monthly burn rate
Lets dig deeper.
4 months from starting is a reasonable time to assume that you are making a monthly profit. So you need to keep 4 months recurring plus the fixed expenses to start.
- Cost of incorporating a legal entity: A1
- Cost of hardware(Computers, printers) to start: A2
- 1 year of insurance for founders and employees: A3
- Deposit/Down payment for office rental: A4
- Miscellaneous one time costs (Buying a domain etc) A5
- (Lets assume two people) Salary B1/Month: 2 * 4 * B1
- Electricity, Janitorial, AC etc: 4 * B2
- Cost of web services used(Project management/CRM): 4 * B3
- Cost of servers: 4 * B4
Put these values in a spreadsheet and get the amount of money you should get before you start. In general between 5-9 months of recurring expenses are a fair estimate.