My first ride (in the yard) was on my grandfather's Yamaha DS7. I was probably 3 and sitting on the tank.
He bought it the year I was born, and upgraded to a Honda CB400F in 1976.
It was also my first bike. 18 years later. In 1990, I cleaned it up, got it running, and put it on the road after years of it sitting in the back yard. (My dad had "inherited" it in 1976 and rode it for some years afterwards.) My first ride on it at that point would have been up and down the gravel driveway in front of my house.
And here's the best part of the story. I still have it. It's sitting in the weeds outside my garage awaiting a complete restoration. (Although I'm going to need a complete donor bike to do it...) It's 40 years old, and I hope my son (or one of my daughters) will ride it someday. A 4th generation experiencing such a classic will be awesome.
The 1976 Honda CB400F is also still in the family. My sister has possession of it at the moment, though it isn't being used. If I ever get the DS7 done, I hope to talk her out of the 400F.