>the hive is a single brood box and 2 supers
What size are the boxes? Assuming a deep brood box and medium supers. I would probably start feeding them if you do not have a strong fall flow. I can overwinter with a full deep and medium box. I assume that you will need at least that, so you may need them to fill out that second super. They will only build new comb if they have something to put in it.