Jonathan (Edwards) was in Portland for a meeting, and came to see me in my office at PSU. This was Monday, 19th July 2010, according to my email archives. I don’t recall dinner, but that doesn’t mean that it didn’t happen. Jonathan gave a talk at PSU: "my typical brew of high-level radical ideas, rather than stuff that counts as publishable results in our field. I'll leave it to you to judge whether that is what your audience would enjoy. That is the same material that I am seeking your advice about." (The talk was about "Declarative Objects"; I found the abstract.)
I recall arranging for Jonathan and I to meet with Gilad in a coffee shop over by Lloyd Center, which is close to where the meeting (Emerging Languages Camp?) was held. On the 20th, Jonathan sent me a "quick cut at some points for a manifesto". By 3rd August, I was circulating a draft of a manifesto that we eventually sent to a list of PL researchers, arguing for the creation of a new IFIP Working group on Programming Language Design, with aims and scope, and inviting the addressee to be an initial member. At that time we had a list of about 20 initial invitees (which I have, but which might be better kept private).
On 27th August 2010, the original invitation was sent to the mailing list at pldesign@..., presumably so that it would be in the archives. The manifesto is also on the Wiki page of the -1 meeting in Reno — see below.
Concurrently, I started looking into what being an IFIP group would involve. I contacted Rich Hehner, who I knew from w-a-y bay, and who was a member of WG 2.1. Rich got me invited as an observer to the WG 2.1 meeting in Atlantic City (19–27 September), where I was able to see one take on how to organize a WG meeting. (Many years later, I was invited to join WG 2.1.)
Once we had positive responses from a number of people, we had lunch together at SPLASH in Reno (19 October 2010) to talk about our zeroth meeting. This is recorded on the original Wiki (now here) but the list of attendees is incomplete. I’m pretty sure that Mark Miller was there, because we held the 0th meeting at Google in Mountain View in June 2011, with Mark and Jan (who had by that time moved to Google) as hosts.