During Campaign Setup:
During the campaign setup, simply click the date shown under “Start Date”. The date shown will be the earliest campaign date that is available for the genres you have selected. You can leave this date, or select a later date from the calendar.
Note: your campaign start date is the day your track will be sent out to curators. You can view the How long will my campaign run for? article for more details on the campaign process.
After your campaign has been scheduled:
If you have already scheduled your campaign, you can change your date anytime before the campaign start date. Just visit your "My Campaigns" page and click the blue "Change start date" button