I signed up for the email mailing list two years ago and got a PCE invite code. Then I bought a tiny ~$30 item at the FP boutique and started getting mailers every single time there was a PCE, even though I've never used them. Interestingly, since I spent $200+ sans PCE code, I haven't received anymore invites. Lol I was verbally told by an SA about Thanksgiving ish events after I inquired, matching the above breakdown by momtok.
Same. I bought a ~$40 keyring way back when, and started getting PCE's through the mail and email. After the borough bags debuted, my spendings at Coach spiked, and I've continued receiving invitations ever since.