Well, I know that they say nothing other then breast milk until 6 months, but that has been different in our family.
Ethan started showing a desire for food just before his 3 month birthday. He was watching us eating, and often mimicking our chewing. So after his 3 month mark, I started to give him little tastes of things.
First it was watermelon, then a popsicle, then some honeydew melon, cantelope, and cucumber. We would use the little mesh food bags with fruit to let him chew on them and get all the juices. He loved it. He would actually cry when it was done or taken away.
At around 3.5 months we started to give him other foods when they were on our plate. Things like sweet potato, mashed potato, squash. He loved them.
Ethan got to the point where when ever we ate dinner, he would cry for food. I would try to give him milk, and he would refuse. He wanted food. He wanted what we were eating and that was that. So for the last 2 weeks, he has been getting more then just little tastes. He has been getting a full meal each day for the last week. He has had 2 types of squash, mashed potato, pumpkin, sweet potato, apples, mixed fruit, carrots, peas and rice cereal. He has LOVED them all.
I am making his food, and it so far has been so easy. It has taken a total of maybe an hour to get a freezer full of the above foods! Now, we have a good chunk of his 'first stage' foods and we will easily be able to defrost a meal each day for him.
He is of course still primarily breast fed, and he still likes his milk. He usually has some before he eats and after!