In the Campaignyou can choose the time of sending your email. Either immediately, at a relative time or you can also select a specific date and time.
In the period in which the e-mail is “Published”, it is also sent to all contacts who are added to the segment. It may make sense to set the unpublished date in 1-2 weeks. You should plan at least 2-3 hours lead time, then the emails will certainly have enough time to be sent. However, this always depends on the number of your contacts.