Android MobileAds loads ad too long

I want my Android application to display ad – InterstitialAd. I want it appears after the welcome screen. It means that I have WelcomeActicity that appears on app start, and recently after this – the ad is displayed.

I create InterstitialAd and start loading ad in application’s OnCreate() method. If application was closed for the long time, ad loads for more then 13 seconds. Of course this is inappropriate – user should not wait for so long. I made this tests building release apk that was directly installed on my phone Xiaomi Redmi 4X.

So the question is – should it be done in some other way? Or ad is always loaded for the long time and I just need to move it forward in user’s workflow?

In app's OnCreate() I start loading

public class MyApp extends Application {

    private FullScreenAd mFullScreenAd;

    @Override
    public void onCreate() {
        super.onCreate();
        mFullScreenAd = new FullScreenAd(this);
        mFullScreenAd.loadAd();
    }
}

Implementation is the following:

public class FullScreenAd{

    private static final String APP_AD_ID = "ca-app-pub-3940256099942544~3347511713";
    private static final String SCREEN_AD_ID = "ca-app-pub-3940256099942544/1033173712";

    private String mAdAppId;
    private String mAdScreenId;
    private InterstitialAd mInterstitialAd;

    private long mLoadStart;

    public FullScreenAd(Context context) {
        super();
        DebugLogger.d();

        mContext = context;
        initAdIDs(null, null);
    }

    private void initAdIDs(String adAppId, String adScreenId) {
        DebugLogger.d();

        mAdAppId = (adAppId != null) ? adAppId : APP_AD_ID;
        mAdScreenId = (adScreenId != null) ? adScreenId : SCREEN_AD_ID;

        mInterstitialAd = new InterstitialAd(mContext);
        mInterstitialAd.setAdUnitId(mAdScreenId);

        setInterstitialAdListener();
    }

    public void loadAd() {

        // Initialize the Mobile Ads SDK.
        MobileAds.initialize(mContext, mAdAppId);
        AdRequest adRequest = new AdRequest.Builder()
                .addTestDevice(AdRequest.DEVICE_ID_EMULATOR)
                .build();

        // Start loading the ad in the background.
        mAdIsLoaded.set(false);
        mInterstitialAd.loadAd(adRequest);
        mLoadStart = System.currentTimeMillis();
    }

    private void setInterstitialAdListener() {
        DebugLogger.d();

        mInterstitialAd.setAdListener(new AdListener() {
            @Override
            public void onAdLoaded() {
                DebugLogger.d();

                DebugLogger.d(String.format("Ad loaded in %d ms", System.currentTimeMillis() - mLoadStart));

                mAdIsLoaded.set(true);
            }

        });
    }

   public void showAd(OnAdClosedAction action) {
        DebugLogger.d();

        mInterstitialAd.show();
   }
}

Loading an AddMob interstitial ad takes some time. Usually it's as quick as a few seconds, but can go up to 20-30 seconds if the connection is poor, or the ad contains animation/video. It might even not load at all!

A good practice is to load and keep in memory the ad upon app launch, and show it later at some point - make it all as seamless as possible. Make sure that ad loading/displaying is not interfering with user experience - don't make the user wait for your ad loading.