For us, it was around 7 months.
I'm not sure if it really qualified as a "real tantrum", but it sure looked like one.
He'd want me to give him something, I wouldn't, and he'd totally freak out.
It was at it's worst around 13 months...but now, at 15 months, the tantrums seem to have gone "into remission" for the moment (for the most part).