Scheduling provides a mechanism to automatically change the properties of a rule depending on the time of day or the amount of data that has been transferred by a user.
It works by allowing the administrator to attach triggers to a rule that are fired when the specified conditions are met. The result of the trigger is also specified by the administrator.
Scheduling is performed on a per-rule basis where each trigger has a corresponding rule. Each rule can have up to 100 triggers each but in most cases only one or two triggers are necessary.
To create a new scheduling item, click the scheduling tab in the manager window. Right click an empty area and select New ....

This will open up the Trigger Properties window:

The top half of the window allows you to choose the condition that must be met for the trigger to fire. Choose one of the 3 options:
The bottom half of the window specifies the result of the trigger. Choose from the 3 options:
The rule that the trigger applies to can be selected from the Rule list. The trigger's action and effect will apply to the selected rule.
There is also a checkbox at the bottom of the window that creates a dynamic trigger. This applies the trigger to each user of a dynamic rule individually, rather than all users as a group.
Dynamic triggers will fire after a user has transferred the specified number of megabytes, and does not affect other users in the dynamic rule. That is, each user is given their own transfer limit and is speed limited when they reach it. Dynamic triggers are recommended over normal triggers when dealing with dynamic rules as they do not group users together when calculating the amount transferred.
Note that only the After X megabytes trigger and Set maximum rate action are available for dynamic triggers, as the other options always apply globally to a rule.