IME, finding people online who are even remotely compatible online -- much less IRL -- is a HUGE time-suck.
Eithyer way: the more you expect, the longer it'll probably take. You're super-vague as to whether you're building a commune or hoping for a stable open quad or looking for "the girl of your dreams" to forever be with you in a closed triad.
A memorable one-night stand? Easy.
Months of steady dating? Doable.
One unicorn & done? Well... you got a few years to do little else...?
IME, there's plenty of places I've met people who became lovers -- & this was back in the 1980s which really oughta be considered The Middle Ages (at best!) by polydom.

We met potential lovers EVERYWHERE because we were open about our lifestyle & willing to discuss it in public -- more than once, a woman would ask US out to dinner to talk more! Some situations we met people --
- monthly meeting of a local BDSM site
- local Naturist events
- nudist camp
- science fiction conventions
- Renaissance Festival
- Morris parties
- community Wiccan rituals
- public dances & get-togethers of a local swinger club
- meetings/get-togethers of gay/lez/bi folk
Not to put a fine point on it: if this poly thing is any sort of burning desire for you, it'll be easy to attend a half-dozen such events by July.
Anna & I were obviously happy together, but NOT in a joined-at-the-hip manner. We were calm, we knew what we wanted, & we were there to relax & socialize so we DID NOT engage in any "better than" debates, & sometimes would skirt around the poly issue & have a pleasant time. Why propagandize?

As often as not, people gossiping (negatively) about our lifestyle resulted in someone thinking "hmm-- that sounds really interesting!"
If your only pool is people who've already made the "leap of faith," odds are a LOT higher that their "dance card" is already full up, & your chance to shine is waaaaay down on their list.