Administration of Disqualified Player

[chrisathames]

I can't seem to find the correct administration of a player who has received his 5th foul anywhere in the rule book.
I have always been told you inform the coach of the disqualified player and the coach then has 30 seconds to replace. I have always waited for the coaches replacement before awarding the free throws, but the other night my partner tried to tell me that you shouldn't wait and go ahead and begin the free throws.
Can anyone tell me where this would be addressed in the rule book?