Navigation:  System Setup (F4) > Services > Schedule Tab

This tab is required for ALL Services that you setup as Run Mode:  SCHEDULED.

 

The minimum value needs to be a 0 (zero) for either Day of Month, Day of Week, or Every  Minutes. 0 values will cause the Service to ignore that value.

 

You can also specify a specific time of day that this alert should run. You can have the alert run up to 4 specified times. For example, you want the Backup Service to only be ran at 3:00 AM each day. You would put in 03:00 in the Time of Day 1 field.