With Jess I sterilised everything till she was 12 months old. Bottles, dummies, spoons, bowls even the little scoops that come in the milk. I think it's done her more harm than good though cos she picks up everything going and is always ill.
With Aimee I only sterilised her bottles and dummies and stopped when she was about 10 months.
With Nathan I stopped altogether at 6 months and never sterilised any off his weaning stuff.