You can short-circuit the job during the blackout period by using addinfo and map for the blackout period that it is not supposed to run like this (extra steps for clarity):
| noop | stats count AS myHourMin | addinfo | eval myHourMin=tonumber(strftime(now(), "%H%M")) | eval blackout= if((myHourMin>2100),"YES","NO") | eval earliestMaybe=if((blackout=="NO"), info_min_time, now()) | map search="search earliest=$earliestMaybe$ latest=$info_max_time$ YOUR SEARCH HERE"
For the time range that it is not supposed to run, the search will generate an error.
Here are other similar questions with answers that should work for you (this answer is derived from the first one):
http://answers.splunk.com/answering/260370/view.html
http://answers.splunk.com/answers/24824/can-i-set-a-blackout-period-for-a-scheduled-search-during-which-it-should-not-generate-alerts.html
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