How long should damp brickwork take to dry?

Recently had a leaking chimney (now repaired). As a result the chimney breast in the upstairs bedroom became very damp and we've had to remove the plaster. This has revealed the damp bricks below. It's been about a few weeks since the bricks were exposed, but they don't appear much drier yet. How long should damp brickwork take to dry? I'm currently leaving the window open as much as possible and have tried using fan heaters and a dehumidifier. Any advice would be much appreciated.