When to ask for payment information?

I am looking to improve the onboarding & initial experience for users of a mobile app. It already includes a basic signup form (email, password, first/last name), phone # verification, and an onboarding slideshow before the actual content/functionality of the app.

Where would cause the least amount of friction/be more user friendly: Request users to add their credit card during profile setup, or on checkout when they are placing an order?