Bees naturally move upward, so you want to get them to expand the brood nest sideways as much as you can. I wait until they have started on the brood side of the outside frames before adding upper boxes. You have to be careful at that point, if the bees have a tendency to swarm, they might want to build queen cells.
OK. What will I have to do if they build queen cells?
How many frame boxes are you using?
If you mean the frame capacity of the boxes, these are 8-frame boxes. If you meant the number of boxes I have, I have bought 4 hives, one of which is expected to be set up in a day or two. I will have 3 spare brood chambers and honey supers each, in case I can use them to build more brood combs or store more nectar.