When setting up bidding for Performance Max, you have two main options:
Recommendation: Run your campaign on "maximize" settings (either maximize conversions or maximize conversion value) without targets for the first couple of weeks. This allows Google's algorithm to gather data before implementing target ROAS or target CPA.
After setting bidding strategy, configure your location targeting (country selection) and language settings based on your target market.
When determining budget, allocate enough to allow for several conversions per day.
A good rule of thumb is to set a budget that's a multiple of your average conversion value.