A real evening
Phones are often useful: directions, a family text, the game-group thread. The goal is not purity; it is helping conversation win when it can.
A little structure
A small tray or side table offers an easy cue without a rule. Put your own phone there first and the room usually follows.
Make room for ordinary life
If someone needs her phone nearby, nothing has gone wrong. Welcome is more important than a perfectly styled ritual.
Keep the promise modest.
This is social guidance, not medical or mental-health advice.