Right now most new beekeepers have their third box on or the second box is done and supers are on.
The third deeps are close to being full. If the third deep is full of honey do not do a reversal. This honey is the bees winter honey. Putting it on the bottom will give the bees no room for the queen to lay because they will fill up the new top deep with honey also. That is too much honey for the colony.
Leave that top deep full of honey as the top box and put on honey supers.
Honey supers have to be put on if the lower boxes are done being drawn out. Some new beekeepers want to save all the honey for the bees and not put on supers. The result of this is the bees will fill up the hive with honey leaving no place for the queen to lay. The colony population will go down and the bees will not winter. So supers on when the hive is ready.
When the supers are new I usually put them on without a queen excluder at first. Once the bees start drawing some comb and putting a little nectar in the first box, I then slip in the excluder. Most of the time the queen does not slip up here. If she does, I find the frame she is on and pull the supers off, I gently coax her off with a little smoke while the honey frame is resting on top of the deep frame of the top box. The bees will get off the super frame and move down into the lower deep box.