My DS1 started tantrums at 11 months, fortunately, he was my first so I didnt have to cope with dealing with any other children at the time. There has been loads of threads on here about little ones starting the tantrum stage early.
I would try to head off any tantrums if you see them coming on -ie distraction. Dont give in to any tantrums though - you will just be feeding the next. And ignore, ignore and ignore but make sure that when he calms down you turn your attention to him and give him a big cuddle. Sometimes DS1 got so beside himself that putting him in his cot was the only thing to do until he calmed down - to keep himself safe and any others near him (head butting and biting). hth