the normal bb/hr rate for 3/6

This is my first time posting...I was wondering if anyone can tell me what kind of bb/hr rate I should expect at 3/6 hold em. I have been averaging 2.5 bb/hr, but could this be just a case of cards falling my way or is this realistic?
I have only played 6000 hands since I moved up to 3/6. Also, when is the ideal time to move up to 5/10? After a certain bankroll? What kinda rate should I have at 3/6 for it to be safe to move up?