I would go flaps first (either up or to the stage of flap required)then full power. My reasons- with full power selected I wouldn't want the student to be reaching down and possibly looking into the cockpit as the speed builds up to rotation speed.
Also the flaps could be forgotten if the student puts full power first and then starts to concentrate on holding the centreline.
With a student once in a Cessna 182 -landed with full flap. He added full power and forgot the flaps. We went up like a heli with all that power.
[This message has been edited by Honest Frank (edited 06 May 2001).]