There is a very loud nest of birds in my chimney. How long until they fly away?

They hatched about 4 or 5 days ago and have gotten louder and louder. I have closed off the fireplace so they don't fly into my house. They are driving me crazy. How do I get rid of them or how long until they fly up the chimney? I think they are prob Blue Jays as there are many around my house.