wow, am I glad I found this discussion. I was trying to teach my niece Concentration, and didn’t remember some crucial parts. Now here is how I played it as a kid:

Concentration/are you ready/if so/let’s go/starting/with names/of boys/one apiece/no repeats…
then the first girl shouts out a name beginning with the letter A, the next girl shouts out a name beginning with B…