I’d work on the emotional state before I work on the tactics.
The first ten minutes feel important because everything is new — opponent, pace, space, crowd noise, score. Some players respond by trying to do too much too quickly.
Give them two or three simple opening behaviours: first pass secure, midfield stay connected, back line communicate early. Nothing more complicated.
You can also recreate “first five minutes” in training. Start a game suddenly, make the score 0-0 and ask the team to establish control before chasing chances.
I would avoid telling them to calm down. That is hard to act on.
Give them something they can do.
At U14, intensity is useful; panic is not. The aim is not a slow start. It is a clear start.
Once players learn that they do not have to solve the entire match in the first two possessions, their normal football usually appears much earlier.
