My son did everything early: rolled over, crawled, and is now about 10 seconds away from walking on his own at 9 months! Despite all this, he only just started holding his own bottle 2 weeks ago. The key for us was 1)switching to a sippy cup (we use the Born Free with handles) and 2)laying him on our bed with his head on a pillow. He immediately grabbed the handles, and has never wanted us to help him drink again! We just lay next to him and keep him company. :)
Don't worry- he'll do it if and when he wants to. It's definitely not a milestone, though. He sounds very advanced, so I don't think you have anything to worry about!