The biggest problem I see with grass roots referees, especially those fairly new, and even more especially when they played or at still playing, isn't related to the timing of advantages and pulling it back if necessary, rather it is what constitutes an advantage. Michael Oliver and co might get away with playing advantages in the defensive third, but that isn't appropriate at grass roots levels. Think of advantage as traffic lights ...
Defensive 3rd: RED, don't play advantage unless the fouled player literally has an entire empty pitch to run into.
Middle 3rd: AMBER, only play advantage if the fouled player is facing towards goal and has clear empty space to move into
Attacking 3rd: GREEN, safe to play advantage but still look at factors like is he surrounded by defenders, would a free kick be a better advantage, how wide is he, etc.
Remember that you have to look at more than possession for advantage, position is equally important. I observed an L7 last season and he played 17 advantages, all signaled well with voice and arms. The problem was that only one of them was what I would call a real advantage, the rest were just the fouled player keeping possession of the ball.