There have been several warmups before. In Vienna at the WordCamp EU we had even different Warmup Events at once. We had a meetup, a picnic, a tour thru Vienna, a warmup evening and so on.

https://2016.europe.wordcamp.org/arriving-early-to-vienna-join-other-awesome-people-at-one-of-our-volunteer-organised-warm-up-events/

In germany we have the tradition of a warmup evening since years. It's a very nice evening for meeting other people. But it's really nice to hear, that you do it now too! :)