Earliest I can go back is 3-5. I've never tried to pin it down, but it'd take famlily corroboration. Questions like
"Hey, Dennis (my brother, he's 5 years older) when did you get that battleship foam thinking with the wire-controlled helicopter on it?"
Dennis: "You mean the one you broke on the second day I had it?"
Me: "um, yeah, that one....."
There's probably gifts that I remember...opening my Fisher Price Castle on Christmas, and liking the little chair with desk almost as much...that don't involve me breaking something of my brothers, but not as many. Like the time I broke his rubber band balsa wood plane. I tried to jump over it, but apparantly I used to be pretty clumsy.
I can remember other things from about that time, like getting thrown off the ladder to the bunk bed by the mean kid across the street. He's the same kid that made me (he was older, so of course he could make me...I was 3 or 4, remember?) stuff leaves down my pants.
Maybe there's a reason I don't recall much. I also remember the time I kept walking in front of my dad and messing up his Grand Canyon pictures. His shots would alternate between the top of my head and his thumb. If he was really lucky, he'd get both.