I just stay behind them. There's no reason to try to get in front, too many cyclists seem to assume that bike boxes are the target destination and squeeze through wherever to get there. It's not always safe to do that, what if the lights turn green while you're between a bus and a railing and he's turning into you? Also, Why filter down the left to get to the box when you're turning right? Just stay where you were a few cars back and position yourself in good time in front of a car that's already seen you. Keep vehicles that haven't seen you, in front of you.