首次启动应用程序时，InterstitialAd不起作用

Question

我正在尝试在启动屏幕之后立即开始投放广告。请告诉我为什么在首次进入应用程序后，安装后立即显示广告，以及如何解决该问题？重新输入后，效果很好。

    private lateinit var mInterstitialAd: InterstitialAd

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.splash_screen)

        if (!SubscriptionProvider.hasSubscription()) {
            mInterstitialAd = InterstitialAd(this)
            mInterstitialAd.setAdUnitId(this.getString(R.string.interstitial))
            mInterstitialAd.loadAd(AdRequest.Builder().build())

            mInterstitialAd.adListener = object : AdListener() {
                override fun onAdClosed() {
                    super.onAdClosed()
                        startActivity(Intent(this@SplashActivity, MainActivity::class.java))

                }
            }

            Handler().postDelayed({
                if (mInterstitialAd.isLoaded) {
                    mInterstitialAd.show()
                } else {
                    startActivity(Intent(this@SplashActivity, MainActivity::class.java))
                }

            }, 4000)
        } else {
            Handler().postDelayed({
                startActivity(Intent(this@SplashActivity, MainActivity::class.java))
            }, 2000)
        }

    }

}