If you would like to send customers to a page prior to them seeing the sales page you can use the Pre-launch option. This could be to gather email addresses, have customers sign up to a training series prior to your launch, or even if you simply want a bridge page with the buy button on the the following page.
If you want to send all affiliate traffic directly to your sales page after launch date/time that you set you will need to toggle the button next to "Automatically send traffic to Sales Page after launch date/time." If left toggled off (as shown in the above screenshot) all of your affiliate traffic will go to your presell/landing page/pre-launch page until you change the URL or remove it.
You can also use this option to set up a free product. To learn more about setting up free products on JVZoo you can read the article here.