SLA rules not applying to tickets that come in after business hours

I have set my company SLAs for 4 hours and a warning at 3 hours. The team operates from 9 am to 740pm EST. When tickets come in outside this window, no SLA rules apply to them. When I read articles, it says that if a ticket comes in, say, 1 hour before the end of business hours, then the next day, you will have 3 hours to answer before the breach, but this is not working for me. Any insight is appreciated.