To initialize Amplify Push Notifications, you will first need to configure Amplify.

Import and load the configuration file in your app. It's recommended you add the Amplify configuration step to your app's root entry point. For example, `index.js`

```js
// Example index.js
...
import { Amplify, Notifications } from 'aws-amplify';
import awsconfig from './src/aws-exports';

Amplify.configure(awsconfig);
...
```

Next, enable Amplify Push Notifications. You should do this in your app's root entry point after configuring Amplify as push notifications can occur even while your app is in a terminated state.

```js
// Example index.js
...
Notifications.Push.enable();
...
```

Your resulting entry file should look something like the following:

```js
import 'react-native-get-random-values';
import 'react-native-url-polyfill/auto';

import { AppRegistry } from 'react-native';
import App from './App';
import { name as appName } from './app.json';

import { Amplify, Notifications } from 'aws-amplify';
import awsconfig from './src/aws-exports';

Amplify.configure(awsconfig);
Notifications.Push.enable();

AppRegistry.registerComponent(appName, () => App);
```