Started riding 7 years ago. First bike was a '89 Honda Hawk GT (NT650GT). Owned it one month before upgrading to a 2006 R6, which I owned only six months before upgrading to a 2008 CBR1000rr.
Yep, I'd say I went head first into the sport. But do I feel like I went too big too fast? Not really, although that's how I voted for the poll...
Back story: I had ridden a friends dirt bike around a field maybe a hand full of times prior but had tons of mountain bike experience, if that counts for anything. Wanted to get my M1 license, so I took the MSF course. Went with the Hawk GT as my first bike due to my dad's recommendation. It's a great bike. However, my friends had sport bikes and I was wringing the Hawk's neck the way I was riding it. It didn't stop super great (one front rotor) and had charging/alternator issues that were holding me back. Quickly dumped it for a R6 that was quite the change from a riding perspective. Then stepped up to the 1000rr that I kept for about 2 years. The occasional dirt bike experience in between, but never owned my own dirty bike at that time and the experiences were pretty mellow.
It was at that time that I finally realized why it would be desirable to ride a smaller displacement bike. I sold the 1000rr for a 600rr, had that for a year or two. Then I discovered I could have multiple bikes and bought a CBR250r for commuting while also owning a street triple. In a lot of ways I feel I did things backwards. I'm really too big for a 250 and when I tell people I owned one I usually get a puzzled look. But there is nothing like learning how to keep momentum when on a small bike.
Knowing me - and my personality - there is no way I would have been happy with a 250 from the get-go. I would have described it as gutless and under powered instead of realizing the challenge it presented to help me up my moto skills.
Happy to go into more detail if you want it for your story.