Comment by embedding-shape

Easy two-part process: First part is putting our "feelers", ask/tell a bunch of people "You know, I'm thinking of maybe hosting a dinner party/barbecue/beach day" and see what reaction you get from people. If sufficient people (sometimes just 2) give somewhat interested vibes, ask again what dates people could do it at, then you send out an invite.

You'd get a bunch of people who say yes but then don't show, this is normal and don't take it personally. Secondly, maybe the first 2-3 times it'd be hard to get people to commit, but once you do it more regularly, people will find it easier to commit to something they know you're already committed to.