It is very common to prepare a message that you will not send immediately, but on a specific day and time.
Once you select your audience and compose your message, from Delivery Settings you can schedule when the messages should be sent.
Scheduling is as simple as setting the selected day and the time you want the messages to be sent.
You will also be able to edit or cancel a scheduled campaign, and to reselect the audience.
You may also be interested in knowing when is a good moment to send the campaign.