It's important that leads can't schedule their intro too far out.
Limiting how far into the future they can schedule an intro appointment can be done with the follow steps
Log in to The Follow Up Ninja
Go to settings (scroll down on the left)
Click the "Calendars" tab
Find the calendar you want to edit (It should be the calendar you are using for intro appointments)
Click the edit button (it looks like a pencil)
Under "Date Range" enter the number of days you want your lead to schedule in advance.
Scroll down and click "Save"