[notifications] Add jsInitialised method to improve getInitialNotification

lib/modules/notifications/index.js

@@ -2,6 +2,7 @@
  * @flow
  * Notifications representation wrapper
  */
+import { Platform } from 'react-native';
 import { SharedEventEmitter } from '../../utils/events';
 import { getLogger } from '../../utils/log';
 import ModuleBase from '../../utils/ModuleBase';
@@ -119,6 +120,11 @@ export default class Notifications extends ModuleBase {
         );
       }
     );
+
+    // Tell the native module that we're ready to receive events
+    if (Platform.OS === 'ios') {
+      getNativeModule(this).jsInitialised();
+    }
   }
 
   get android(): AndroidNotifications {