I went in August after I arrived - on the advice of some friends who had gone along. We had received invitations from the Kreisburo (different Kreisburos seem to send the invitations more efficiently, I think we decided there) It was useful: a multilingual introduction and walking tour, followed by an apero - a few of us then went on to a bar afterwards and met up a couple of times after.
Though you must register, they don't check (hint: EF event crashing potential

)
It's run by the Zurich integration office:
link
The public invitation and the dates that it is run are
here
As the OP said - what other city??!