People who started local marketplaces, how did you get first few users (who weren't friends/family/coworkers)?

If anyone has started (or saw other people start) a city-based marketplace, how did you get the first few strangers as users?

Recent advice suggests to start with supply-side (ie. the side that doesn't mind "waiting"), which makes sense. A few ideas I'm considering for my events marketplace:

• Linkedin cold-message people active in similar marketplaces and invite them to interview + build profile in person (ie. AirBnB with craigslist users); maybe even find specific businesses who advertise with local newspapers/sponsor events
• Create profiles on local business behalf & cold-email them asking their permission to publish / give them opportunity to edit (ie. Yelp's start)
• Organize event where people create profiles at-the-door (ie. Tinder with sorority parties)

I think the intention after getting a few supply-side users, is to then reach out to demand-side saying, "we already have X, Y, Z signed up so check us out".