A secret poker game you can play on the subway

It’s not clear to me when or how you “choose” your row of 5. I feel dense but I don’t think this is described…

Notice the image which says “A pair of aces is a good start”, because two elderly people are sitting there. Think of it like each row being a pre-populated hand (which may be missing some cards) based on the people already sitting there. You pick it and then the “cards” change themselves between stations.

In other words, you pick immediately once the game starts. Look around to see which row you think has the best chance to develop into something good by the time you reach the designated station.