Players directed to leave and timeouts during the 20 sec period

[tadams]

These are two other questions presented by Rulebox, I am not 100% on the wording but I am sure I have the intent of the questions right:

Scenerio 1: Player A-1 is bleeding and directed to leave the floor. At the end of the time out A-1 is ready to play. He is allowed to play.

Scenerio 2: Player A-1 is bleeding and directed to leave the game. Prior to A-1 being replace, Team A requests a time out and is denied.

I understand both rules... so when does the coach call the time out? Once the official directs the player to the bench a replacement needs to be made before a time out but if the player is replaced then he needs to sit for a tick before reentering...

How does this truely play out in real life? Is it that the coach has the timeout/replacement option prior to the 20 second clock starting?

Thanks again.