This might not make sense to you, but if a song comes out with your work sampled, it’s up for sale, and it’s on a major label, they will likely try to get an appropriate license and pay you.  The bigger the song, the more leverage you have, which likely means more money for you.  It's great press, too.  I know video guys that had their data used without their permission for commercials, and they got sizable checks once they reached out and said “hey you didn’t have paperwork for that."  But if you start screaming before the record is commercially released, they might just axe it and you might not get anything.  Your bargaining power increases if you wait and the song becomes successful. Don't wait too long, though. The statute of limitations to bring a civil suit is three years.