Do I need a permit before I start my business in Switzerland?

For non-EU/EFTA nationals, the residence and work authorisation must be in place before any self-employed activity begins. The application is assessed against labour-market and economic-interest criteria, so starting operations before approval is not permitted.

This is different from the EU/EFTA free-movement situation, where citizens can take up self-employment far more freely. As a third-country national you should plan for the approval process to come first and build it into your launch timeline.