Once.
He's a baby. He doesn't have a job. Although he was forced to get one at McDonalds in 'Baby Not on Board' when he was left home alone.
"Baby Not On Board". Stewie is left at home when the Griffins go traveling and he looks in Chris's room and finds the Hustler Magazine.
13 is the legal age for a child to be left alone in the US
How long can a child of 12 years old be left at home alone in the state of Maryland?
They can be left home at any time but the legal age is 12+.
14
Yes Im Sure That He Is
Paris, France
Different people mature at different times ... hard to put a definite age on this answer, but possibly the safest answer is that no child should ever be left at home, alone, but if one absolutely had to, age 16 might be a responsible enough age for some, but not everyone.
Twelve
Sir Dumpalot
Sir Dumpalot