The option to schedule this could be found > under details device > warning activation/multi channel alarm subscription > and when enabling this slide at the top you could see a period schedule option. But they probably (accidentally) removed this option with the last update of DMSS. I still have this option because i alreasy enabled it. Newer app users dont get his option since recently.
edit: Solution for new users (or new install); after logging in or registration. Log out. Then the period setting is available at alarm subscription.
