D-Link DSL-2878 User Manual page 57

Section 4 - Configuration
Schedule: Use the drop-down menu to select the time schedule that the rule will
be enabled on. The schedule may be set to Always, or you can create
your own schedules in the Schedules section. Refer to Schedule on
page 64 for more information.
Click Apply when you are done.
D-Link DSL-2878 User Manual
Port Forwarding (continued)
53