My new blues/rock trio - simply answered an ad in 'Join My Band' in December last year. Went to an audition in early January to play 3 songs, ended up playing the whole set and jamming for 2 hrs
Bon Jovi tribute band - something like 5 years ago I had an idle conversation with @hiram.k.hackenbacker when he mentioned that a drummer he had played with for many years, and who I had known for possibly even longer but not musically, was looking to start a rock band but Warren (=Hiram) didn't think he had time. I saw the drummer (Alan) a few weeks later and mentioned this, we decided to give it a go. I brought in a guitarist I had played with in a heavy rock covers band, Alan brought in both a singer and keys player that he knew. After a few gigs it was decided that a tribute band was the way forward, we did the Bon Jovi stuff in the set well so headed off on that path and morphed into a Bon Jovi Tribute. Which is, I must say, an absolute blast.
Bands before that are ancient history