You can start your free 3-month subscription to Apple TV+ after setting up your new Apple product. Here's how you redeem your offer:
1- Turn on your new Apple device and sign in with your Apple ID
2- Open the Apple TV app. Make sure your device is running the latest version of iOS, iPadOS, tvOS, or MacOS.
3- The offer should be presented immediately after launching the app. If not go to the Apple TV+ channel page where you'll see the offer.
4- Tap Enjoy 3 Months Free