How long until baby birds fly out of the nest?

Usually 2 weeks, then they can fly on their own

Usually for the songbirds (robins, etc.) the babies are ready to go in about 10 days. Once your birds fly the coop, put a piece of screening (weighed down by heavy rocks) over the top of chimney.

Babies will fly when they are good and ready; you have no influence if you don’t want to tamper with mother nature.

Just leave the birds alone and they’ll be gone in a week or so.
Please don’t mess with the mother bird.

Listen to the wonderful sounds the birds make :)

If you disturb the mother to an extent that the clutch fails, it is still possible that they will try another clutch, thus prolonging the “problem”.

Allow the young to fledge, then seal off your chimney with wire mesh before more clutches are laid.