The queen cage in that pic doesn't have a cork in it, it's got fondant in the hole. The bees eat that and release her themselves, slowly. Mine I left her in several days and then just direct released her. Lots of factors involved but normally you want her to spend several days in there until they get used to her and stop trying to kill her before you let her out. In that case you would probably put her in several days iwth a cork and then stuff some fondant in there which takes them a good while to chew off. When I got my bees this spring, They'd been with the queen I got for likely 4 days before I got them so when I installed them I put a mashmallow in there which only takes them a few hours to eat. Slightly more risky. Directly releasing is typically the most risky but in my case it was a good choice.