How do I ask for a review on a mobile app?
Ask for a rating only after the user has demonstrated engagement with your app. For example, prompt the user upon the completion of a game level or productivity task. Never ask for a rating on first launch or during onboarding. Allow ample time to form an opinion.
How often should you ask for a review on an app?
Don't be a pest. Repeated rating prompts can be irritating, and may even negatively influence the user's opinion of your app. Allow at least a week or two between rating requests and only prompt again after the user has demonstrated additional engagement with your app.