sleeper???

I am still pretty new at this game and am still trying to get acquainted with CMT jargon. "Sleeper"; I believe this implys that a bill that has been entered hasn't had a hit (perhaps it's first hit)over a long period of time. What time span are we talking about??….a year, two years etc.?
Antics had a hit after 1029 days. That note would qualify for a "sleeper", right? Your comments appreciated.

That is definately a sleeper, but it needs to sleep more than 1279 days to get onto the longest life list…