Another vote for the "proper method" here. Having the stoker clipped in and giving full on power immediately from the start allows uphill starts with ease. I say go, she puts both feet in motion as I step down on the pedal that is waiting at the top of my power stroke and clip in. I can clip in on the move so our pedals never slow once they start to move. No pause to clip in that will kill your momentum on an up a hill start. The stronger the stoker the better this method works.

Wayne