For long term absence and vacation planning I would recommend doing the absence registration as early as possible.
To create absence for a worker you can click the menu item as shown below:
You can view, delete and create new absence for the user in this form.
Create new and select the from and to date as well as a absence group and/or code.
Ticking the “Interrupt” check box will cancel the absence the next time the worker clocks in canceling the rest of the absence. If the absence is interrupted the Interrupted flag will be tagged making this absence not active anymore.
Bulk creation:
You can also do quick and bulk updates of absence. This is good for doing vacation planning.
Go to Time and Attendance > Review and approve > Create planned absence
Select the from and to date for the intervals and select the absence job. REMEMBER TO SELECT THE WORKERS by applying the filter in “Records to include”.
Ticking the “Interrupt” check box will cancel the absence the next time the worker clocks in canceling the rest of the absence.
Ticking the “Compose” check box will create one line for each day for the duration of the absence.
Messed up?
If you some how create absence for to many users (forget to limit the filter) there aren’t a way to see absence for all users as a menu item. Then you would need to open the JmgAbsenceCalendar table directly in the development environment or create a new form that makes this data accessable.
Go to the AX 7 – Time and Attendance guide page
dyntips.com by Fredrik Sætre 
AX Fredrik I have never seen this planned absence work. I can define and save an absence registration for an employee. BUt then nothing happens. Somehow it has to create registration records that have to be calculated and approved and transferred. Nothing like that is happening