Please establish again when you started hives - May 6th?
Nucs or packages? New comb, or drawn?
If nucs, consider opening to 2nd largest - they will almost immediately begin defending the hive, because they have something to protect.
If packages, I would keep it on the smallest for at least 2 weeks until they have some brood and stores to protect to prevent robbing.
Other than vent issues, I have noticed that my nuc gets right down to normal business re traffic in & out of hive. Packages are confused and there is a lot of hive orientation that takes place initially (circling about in front). You also probably had a fair amount of dead bees in the package when you shook it out that they will remove.