When exactly does a soccer referee blow his whistle?
The whistle is blown when it is necessary to stop play. Just because the ball has gone off the pitch (including a goal) does not automatically need a whistle. If it’s obvious to all the players, just give the signal for the possession and move on. If it exits the field and everyone keeps playing, use the whistle. A whistle is mandatory for any kick-off and before a penalty kick may be taken. A whistle is optional for a direct or indirect free kick. If you have to make it a formal restart (i.e. set a wall or something) then you tell the kicker they must wait for your whistle. Otherwise, give them the option to take a quick free kick.
