When creating a new promo, you have the option of inputting three different dates that impact how your promo is consumed and understood on our system. Located on the promo creation page, the section in question looks like this:
Here's the meaning/use of each date -
Release Date: When your album will be available to the public. This information appears in your invitation, as well as on the promo page itself.
Live Date: When you want your promo to be available to the media. You do not have to make your music accessible as soon as you upload it if that is not your desired launch time.
Expiration: When you want the promo to expire. Any attempts to access the promo on or after this date will fail.