The request for a time-out is made by the coach by showing the official hand signal. The purely verbal request is not a valid request! The second referee must always wait for the hand signal before granting the request.
The request for a substitution is not made by the coach, but by a player entering the substitution zone ready to play. Any additional substitution players must arrive at the substitution zone not causing a delay.
The "substitution hand signal" by a coach is not understood as a request by the referees. No delay of the match due to this hand signal is allowed.