No Frank, they don't need to bloom before harvesting. You can harvest them
any time if they are big enough to eat (so long as they aren't green of
course).
Dig one up and see. If potatoes present, you have your answer. If
potatoes are small, keep hilling the plants.
Linda H.
I would remove any dead/damaged leaves and wait for the plant to dry a
bit. ymmv
Linda H.