Do you encourage quick free kicks at U12?

I would encourage the players to look for the quick restart, but not make quickness the target by itself. Use three checks: is the ball in the correct place and stationary, has the referee allowed play to continue, and does the restart create an advantage? They should wait if the referee is managing a card, moving the wall or clearly controlling the restart. They should also wait if nobody is ready and playing quickly would simply give the ball away. A good training habit is to let the player taking the free kick decide, then ask what they saw. At U12, the useful learning is recognising when the opponent is disorganised and when the team needs a calmer restart. The cue can be: look, listen, choose. That gives the players ownership without asking them to rush every free kick. Wait when the referee is controlling the restart, the ball is not correctly placed, or your own team has no useful option and the quick kick is likely to surrender possession. Quick should mean an advantage is available, not simply that an opponent is distracted.