Building a "Directional Twinkle"

For an upcoming production, I will be programming an LED star curtain (single color nodes, not RGB) with 48 controllable points. In effect, having the ability to have the drop twinkle from bottom to top, left to right, etc. Creating the typical random twinkle like a fiber curtain will be simple, but any ideas on how to make a directional effect in which each star only turns on and off once?

Complicated step based effect that only runs once? Individual delays on each node? Absolute effect?

Any Ideas?

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