Unity Ads when Internet not available in starting game , how i can iInitialize, in during game when internet be available?

I ' m using unity3D 5.4.2f2, and Unity Advertisements Service window. So used at first. this script for making Off initializeOnStartup.

 using UnityEditor;
 using UnityEditor.Callbacks;
 using UnityEditor.Advertisements;
 
 
 public class UnityAdsBuildProcessor : Editor
 {
     [PostProcessScene]
     public static void OnPostprocessScene ()
     {
         AdvertisementSettings.enabled = true;
         AdvertisementSettings.initializeOnStartup = false;
     }
 
 }

After this, I used this line of code for checking.

     void manualAdsInitilizations()
     {
         if (Application.internetReachability != NetworkReachability.NotReachable && Advertisement.isSupported)
         {
             #if UNITY_ANDROID
             Advertisement.Initialize ("###");
             //Android ID
             #elif UNITY_IOS
             Advertisement.Initialize("####"); // IOS ID
             #endif
         }
     }
     void UnityAdsButtonOnLevelFailed()
     {
         if (Application.internetReachability != NetworkReachability.NotReachable && Advertisement.isInitialized) 
         {
             if(Advertisement.IsReady())
             AdsForLavelFailed.SetActive (true);
         } 
         else if (Application.internetReachability == NetworkReachability.NotReachable )
         {
             AdsForLavelFailed.SetActive (false);
         }
     }
 
     // here IEnumerator for checking internet connection
     IEnumerator HandleInternetConnection ()
     {
         while (true) 
         {
             manualAdsInitilizations ();
             UnityAdsButtonOnLevelFailed ();
 
             yield return new  WaitForEndOfFrame();
         }
     }

Is Working when Internet Availabe on start of game , but if start without internet game, and make internet on in during game is not working thank you, waiting for any answers.