Olaf the Stout
Hero
Determining initiative order like that sounds like a good option to keep it simple. Plus the girls know when they’re up next.Whatever order they sit in will determine “initiative.”
“You are a group of adventurers…” Give a clear start that implies what sort of characters they might be and how they know each other. Go around table and ask for brief description of their characters (no complex sheets - if you insist on using sheets there are simplified colorful kids sheets that I recommended, don’t have link atm on phone).
Take note of each - think about each PC’s core competency (+5), what they might be ok at (+2), everything else +0 (if possible at all). Warrior types get 12 hp, magic-user types 6 hp, everyone else 9 hp. Spells are ad hoc based on the “meeting” of the girls’ creativity & your game knowledge.
Use Monsters on an Index Card.
Frame the conflict, and improvise. Set clock for 60 minute mark when something big changes and you start hastening toward a satisfying conclusion.
If you have a link to simplified sheets, that would be great.
I also like the 60 minute suggestion. Possibly the location they’re exploring is about to collapse, so making it out before it does collapse with them inside could be the ending.
Increases the tension and keeps their excitement in the game. Plus that sort of thing is kid-friendly.