Prepare the product experience
Check the store listing, the onboarding flow and the action you want a new user to take. An ad can bring someone to a product, but the product needs to fulfil the promise.
Prepare the measurement
Confirm the events, permissions, account ownership and reporting windows with the app team. Run a small validation before relying on a dashboard for scaling decisions.
Agree the decision rules
Set a review cadence and define when you will continue, pause or change direction. Make space for learning rather than treating the first few days as a final verdict.