I started giving Clare blueberries as soon as they were in season, when she was about 8 months old. They are a great first finger food because they are easy to pick up with little stubby fingers, but also easy to mash with little baby gums. Blueberries aren't related to strawberries and raspberries so I gave them to Clare before 12 months without fear of an allergenic reaction (http://www.wholesomebabyfood.com/blueberrybabyfoodrecipes.htm). At 10 months, she eats them fresh and in pancakes; that is a quite a mess but worth the squeals of delight. I cook them with a little sugar for Bailey's oatmeal in the morning and that always gets me an empty breakfast bowl.
I love blueberries.