What is Scheduled Publish?

Method 1:
Select the page that you want to publish in the future.
1. Right-click on the page.
--> Expand On/Off Time under the Blog Tab
--> Set On time at which the page to be activated
--> click 'Ok'
2. Active page

Method 2:
Select Activate from the menu
-- select Activelater and set date & time

Result: The Scheduled page will be stored in the Publishing server but it will be published on Scheduled time only.

On/Off Time Behavior:
On-Time:
The date and time at which the published page will be activated. When published this page will be kept dormant until the specified time. Leave these fields empty for pages you want to publish immediately (the normal scenario).

Off Time:
The time at which the published page will be deactivated. Again leave these fields empty for pages you want to publish immediately.

Ref: http://dev.day.com/docs/en/cq/current/getting_started/first_steps_for_authors.html