Depends what time zone you were calling from.

The cutoff is midnight in the time zone of the call centre you reach. So if you're in BC, and the call centre you get is in Ontario or Quebec, you should be calling at 9:01pm, BC time. If you waited until midnight BC time, then others had three hours to sneak in front of you.

AC computers aren't very smart. They don't know about things like time zones. Normally that works to the advantage of people who do understand the concept, but of course you need to know about it first.