What is the state of the hive and the combs? All drawn out? All full of stores and brood? What do you want to harvest? If you want nice tender comb honey, I might cut some empty combs off for them to build new ones. If you want to do crush and strain, I'd leave the empty combs for them to fill. If there is a strong cluster and the brood nest is no longer expanding I'd put some empty bars in the brood nest. If it's all full of honey and brood, I'd harvest some honey.