Conversation so far:
When did Tyson start boxing professionally?
Tyson made his professional debut as an 18-year-old.
Who did he fight in his debut?
Hector Mercedes.
What other people did he fight?
James Tillis, David Jaco, Jesse Ferguson, Mitch Green and Marvis Frazier.
Was he starting to become famous at this point?
His win streak attracted media attention and Tyson was billed as the next great heavyweight champion.

Question: When did he get his big break?
Self-contained rewrite: When did Mike Tyson get his big break?