I personally use cocoon.io for ads. It works instantly for me, you should take a look at it. Here's a YouTube tutorial showing how to integrate admob ads using cocoon: youtube.com/watch
The only downside to using cocoon is that they put their splash screen on your app when you launch it (it lasts only a couple seconds).
In case the tutorial isn't clear, these are the steps to adding ads and exporting to cocoon.io:
1) Download cocoon ads
2) Insert the cocoon object into your game
3) Edit the cocoon object and add your interstitial/banner ids
4) Somewhere in your event sheet, (on start of layout for example), you need to put 'load interstitial' or 'load banner' from the cocoon object.
5) Add 'On interstitial loaded' or 'On banner loaded' -> show interstitial / banner
6) Export to cordova but don't minify (doing so will result in a black screen)
7) Go to your exported files and delete config.xml
8) Put all the files into a .zip folder
9) Go to cocoon.io website and upload your project
10) Edit settings and whatnot, go to plugins -> cocoon plugins, scroll down and look for admob-native ads for ios or android or whatever you're using. No need to put ad id's here.
11) Make sure to use canvas+ and export to whatever platform.
12) Ads should load if you did it properly.
That's pretty much it, I just started using cocoon because I found it easy to use and it worked for me