There are many points stand on many possibilities ,those will occur in future.
I think you are going to join in your new school with service continuation. Is not it?
You have written, your commitment date will fall within one month. But (a)the personality test, (b)final result of the SSC (c) the counselling date ,(d) appointment letter from SSC, (e) appointment letter from your new school- I think , your appointment letter from your new school will come when you will in maternity leave. You may join in your new school after getting the appointment letter, but can not enjoy the rest days of maternity leave.
For example :-
** say, your leave will start on and from 15/09/2013 to 14/03/2014.
*** say, you will receive appointment letter on 20/12/2013.
****say, you want to join as early as possible, i.e. 24/12/2013.
in that case you will have to join your previous school to give resignation and to get release order. when you will do so then your leave will stop prematurely. You will not be permission to enjoy the rest maternity leave.
***** You will join your new school after 14/03/2014, if you convince them so that they can wait for you till to date (after 14/03/2014)
Thanks a lot and waiting for goodness.