I would give people a little notice & where I intended to walk to.

Then just announce it:

#PlebWalk 7:30am

From Nakimoto hotel to Satoshi's wharf for coffee (approx 1hr round trip). All Bitcoiners welcome.

I might choose to be selective about what channels I announce it on depending on who I want to walk with.

I find as a general rule, you'll always have at least 1 or 2 show up to any scheduled event. We're very curious & subject to FOMO.