Section 4: Gameplay
Why People Get This Wrong
People often assume that if you have all four cards of a single rank in your hand (like four Aces), they must be laid down immediately upon realizing it. But actually, the rule states you should lay them face up only "immediately" after you realize you have them all, not as soon as you first notice one card of that rank. This can lead to arguments about when exactly is considered 'immediately'.
Official Verdict
Whenever you hold all four of a rank, lay the book face up in front of you immediately.