Scheduled publishing for individual assets
Both the Start Date field (in an asset's Metadata) and the Optionally Publish Later option provide a way to schedule an asset to publish at a future date/time.
See below for notes on when to use one versus the other:
Start Date
The Start Date field, which is part of an asset's Metadata, allows for configuring a specific date and time for when an asset should "go live".
Tip: This is the preferred method to use for brand new pages/files as they will not be indexed in the system or be eligible for publishing until the Start Date has been reached.
Optionally Publish Later
The Optionally Publish Later option, which can be found after clicking to Publish an asset, also allows for scheduling an asset to be published at a later date/time. The main difference between using this option as opposed to the Start Date option mentioned above is that this option will keep the asset eligible for indexing before the configured date/time is reached.
Tip: This is the recommended strategy for scheduling updates to an existing page since the asset is likely already being referenced from various locations throughout the site(s).
Note: This option should not be used for brand new pages/files as it can result in invalid links to the asset from throughout the site(s).