To schedule a follow-up message is simple. From the My Surveys page, scroll the mouse over the title of the survey you want then click on the Follow-up link, the follow-up page will appear. From here, click on the Planning button. Here you can choose who to send follow-up messages to and schedule when to send them, as well as edit the content and subject of these messages.
Once you're done programming your follow-up, your messages will be automatically sent out so that you dont have to worry about it!