android - Solutions to increase ad loading efficiency -

while tracking ads notice high amount of interstitial ads fail load. ads supposed show when user takes major action sending text message. call ads in oncreate in oncreate.

interstitialad = new interstitialad(this); interstitialad.setadunitid("sometext"); adrequest adrequest1 = new adrequest.builder().build(); interstitialad.loadad(adrequest1);  interstitialad.setadlistener(new adlistener() { @override public void onadloaded() { super.onadloaded(); } public void onadclosed() { } @override public void onadfailedtoload(int errorcode) { } });      

is there way load ads when application starts , show ads in oncreate of different activities? think want create method extends application load ads. correct path take? if how call load ad application starts?