It is better to start a game with players who can propel and project your tactics. Vinicius Jr is not that guy that presses enough. Good thing I saw with my own eyes when they played against PSG during the Cwc. I'm cool with him coming from the bench until he learns to press and also add to his defending skills rather than stroll around. I don't watch this football with sentiment, Vinicius Jr need to convince Xabi Alonso into doing that.
Maybe it is part of the reasons most persons see it that Vinicius is not stable with his emotions and psychology most times, he has a mostly independent orientation and so bringing him in later as the game is on is mostly better. He mostly loves to be the play maker but this does not change the fact that he is still good at his position whenever he is at his peak form. Xabi I believe got his eyes on him amd know exactly what to do with him as at when required.