Scheduled completion is 2024, though not more specific than that so may make sense to plan a meet for later.
In terms of a during construction meet, depends on what you're wanting to see and showcase. At this point the perimeter roads and some ancillary bridges are done, and the main approach bridge on the Canadian side (we had to rush on that one to fit the staging for the GHIB). On the US side, the I-75 interchange ramps aren't really there yet. Port of Entry is under construction for both, though they don't really look like much of anything right now. Towers are about 2/3 of their final height.
It's a sprawling project but incredibly interesting.
I had planned a meet on the Canadian side, just was waiting for some things to progress a bit further before doing so. Have you much familiarity with Windsor-Essex? Be happy to work something out there.