The short answer
Track the deepest meaningful event you can get reliably. For a product-led SaaS, that is usually signup plus a key activation step, then later paid conversion or retained usage.
Answer
How do I know paid ads are working?
Paid ads are working when they create qualified actions, not just clicks. For Wally, a strong early signal is someone creating an account and adding a company, because that means the visitor reached the actual product workflow.
How Wally helps
Wally supports qualified-lead event tracking and campaign assets so paid ads can optimize toward users who create an account and add a company, not just homepage visitors.