Hi There,
Thanks for writing in! Actually there is a JavaScript for that.
setTimeout("window.location.href='URL HERE';",10000);
You can add this on Cornerstone > Settings > Custom JS.
But! the preview on Cornerstone will also redirect to that URL you provide, and you’ll have issue editing that page. That means you need to remove the script first before you can edit that page. Just do not set the time lower than 10000ms or else you wont have enough time removing that script on Cornerstone.
Its up to you now, further customizations from here would be getting into custom development.
Hope it helps, Cheers!