I first introduced my bf DS to a bottle at 1 week because I bought a bottle which is, basically, a fake boob. It's called an Adiri BreastBottle (check out their website \link{http://adiri.com/here}) He's now 4mo and has just graduated to an Avent style one coz he got fed up with the slow flow of the Fake Boob (he has a bottle every couple of days on average, I used to express but it's such hard work I soon started mixing it with formula, then gave up expressing altogether).
Has anyone else tried one of these? They're amazing....and you can get them on EBay (new!)