I currently have three hives. Technically one is mine from last year that has done very well so far. My wife has one of the other packages we installed a week ago or so. The third is an observation hive so that is a different story.
My question is on when to add an upper entrance. My hive almost exclusively uses its upper entrance so I'm not sure when I should tell my wife to add one. Currently she has a reduced lower. I'm afraid to open it up too much but her bees are already stacking up.
I'm going to assume the answer is going to be when you think they need it. I was thinking about next week when we inspect the new queen.
It could be from day one or never. I don't have a hive that doesn't have a vent in the inner cover and some bees always use it. So I would have to say you can't make a wrong decision here.
I have two screws in one end of the inner cover, the screws stick up about 1/2 inch. I have the inner cover with screws up in the winter and with the screws down in the heat of the summer. in the summer it acts as a cooling vent and an upper entrence. Just my 2 cents worth. -Mike
If the hive is thick with bees, I would add the upper entrance. That being said, almost all of my strong hives have upper entrances, I built doors into my screen top boards that I can open and close, but some of the hives that started as a bottom entrance, never/hardly ever use the the top entrance.
Jim