Sometimes it may be appropriate to add a listing which shouldn't actually be shown until a certain date. The 'effective time' switch at Admin Panel -> Settings -> Switches enables this option. When the switch is on, a submitter can select the future date on which the listing should start appearing. From the time they submit (and it's approved, if validation is required) until it shows up, it'll appear only in a special future listings area on the member home main page.

If you need to find listings on your site which aren't yet effective, they won't show up in the normal search so you'll need to go to Admin Panel -> Common Tasks -> Search Items -> "Find listings which will take effect in the future".