What options do I have for a sort of Transition page inBetween my optin page and custome URL thank you page that will be a clcickbank vendor product

I build opt-in page with a drag & Drop builder. My custom URL will be a Clickbank Vendor presentation.

Opt-in & Thank you page. There has to be some warning to the person who just clicked for my free gift eBook.

You can't have someone opt-in and then BAM! their now being sold something" They bounce and Delete your ebook"

How can I get a transition page of some kind that last four 4 seconds. This has to be a 3 step system not a two step. opt-in thank you, no way. help"