A good rule of thumb to use is proximity to goal. If it's close enough for a shot or there's a likelihood of a goalscoring chance (maybe there's a wall been constructed?) then use the whistle. (I always tell the players it's "on my whistle please"). If the free kick is inside the team's own half, there's little point in blowing for it.
There's no exact science behind it mate. Generally, unless it's a shot on goal as above, and all players have had time to take up their positions it's not necessary to signal with the whistle. You'll get a feel for it as you do more matches .
I know the Right Hon
@one has already answered... I think there is a more exact science.
If you’ve stopped the game for any reason then a following FK is on the whistle. Sub, injury treatment, card... and typically, depending on your whistle technique and what you are taught, these extraordinary moments are often double beeps. It’s obvious the game is stopped, you warn the player about to take the kick audibly that it’s on the whistle, and you hold up the whistle for the world to see.
For other free kicks, it’s on the whistle only if you say so. So when is that? It’s if you interfere. If you are standing over the ball, getting the ball repositioned, waiting to see if a player is injured... then you are involved and you should prevent a quick free kick and tell it’s on the whistle.
There’s an outlier here... if you end up in a bad position because of a free kick decision and the FK is about to be launched into the box I think the smart ref makes it on the whistle to get into position.
If defenders are standing over the ball and it’s shooting territory, it’s obviously gonna be ceremonial, tell the kicker it’s on the whistle, pace out the wall etc.
Lastly if you don’t have to interfere, stay away from the ball and the kicker. And they might take it quick or normally. If they look at you confused, tell them to carry on. If they still look confused you can ask if they want it on the whistle (see point 2 if there is some kind of set piece lined up) but IMHO getting in a situation where you need to ask the kicker is incredibly rare.
I’ve been taught a pretty clear formula and TBH only just got the hang of staying out of the way unless necessary.
They key is are you involved? If you’ve got involved then make it on the whistle to avoid crazy incidents.
Any regional variation here?