I set my request be responded within 1 days. if not, system will enable Level 1 Escalation.

But I will receive a email before responded deadline. it's usually 10 mins before deadline.

Could I set this time period to 15 mins ago before responded deadline or not ?

ps. the email subject like 

" First Response escalation warning notification. Response due at : Mar 3, 2015 02:15 PM"