We sanded and finished our kitchen floor first, then the buffalo who came to install the kitchen put a big ding in it where he stood the pantry cupboard on it's corner and left some nice scuffs and scratches in it, so I would say maybe sand first and finish after the cupboards, that way it's easier to repair any damage before applying the finish. Either that, or put down one coat of finish over the whole thing and then a second coat after the install.