It depends on the performance of other teams in the FA Cup
Palace are due to play Coventry on February 24th. If Coventry draw their FA Cup 5th round match away at Blackburn then they will replay on the 24th meaning Palace will be free to play Birmingham.
If Coventry win or lose the FA Cup game at Ewood Park then they will face Palace as planned. The Palace v Birmingham game will then be set for March 17th.
Watch this space.