I am not sure what version system you have... but on the Partner, Partner Plus and Partner II you can do the following:
1. From Ext 10 or 11 press [Feature][0][0]
2. press the left [Intercom] button twice
(display will read 'System Program'
3. enter [#][1][0][1]
4. enter the date and time (xx-xx-xx format)
5. enter [#][1][0][2]
6. press [1] for sunday, [2] for monday, etc.
7. enter [#][1][0][3]
8. enter the current time in 24hr format
Hope this helps... if you are looking for a manual for your system, you can find it at
https://support.avaya.com/japple/css/japple?PAGE=Area&temp.bucketID=108025 /Dana