Actions have an attribute named Target Date you can use to set a date within which your action should be performed or completed.
Moreover the read-only attribute Days Left keeps a countdown to the number of days remaining until the target date is reached (and a negative number of days if the target date has passed and the action hasn't been completed). If a Start Date has been set, the countdown will start only after reaching this date.
The action inspector contains a section named Notification where you can ask Hot Plan to notify you when a target date is reached.
If you want to setup a notification, just follow these steps:
Now you are done and on the target date Hot Plan will open its notification window displaying all the actions which will expire on that day or have expired since the last time you launched Hot Plan or, if you have enabled Growl notifications, it will use Growl to show the expired actions.
If you double click on an action, it will be automatically selected in the Hot Plan window.
An alternative method is to enable the Sync With iCal option for your action.
This way a corresponding event will be created in iCal for the target date set and you will be notified by iCal on the day of the event. You can also set various configuration options in the Notifications pane of the preferences window.
Moreover a special hotplan:// url will be created inside the iCal event: just click on it and the corresponding action will be opened in Hot Plan.