I just finished my OPT and had applied for two graduate schools. I got the acceptance letter from school A and before my OPT expired, I transferred my SEVIS to that school, but it is dated on 24th of April. Now just two days ago I received the acceptance letter from school B. I want to go to school B and want to transfer my SEVIS there from school A. School A has not yet issued I20 because SEVIS is dated to transfer only on 24th of April. 

Fax the new transfer out request form to your current school and tell them to discard the previous one.

I would suggest you do both.. notify school A as well as your current school... Better be safe than sorry .
as long as the SEVIS has not be transferred yet, i don't think there will be any problem.

Good luck.

whats wrong with these people. why do u have to post everything in sajha? you seem to have two options that u already know. its not like your status is going to be messed up or you are going to be deported if you call and ask your school or the school that issued you new I-20. In fact you will have to do that anyway, so whats the freaking point of putting that here? don't depend on sajha for every freaking solution dumb ass.
if your gonna say don't comment if you don't have answer to that question, then the truth is that THERE IS NO ANSWER stupid freaking question.

Thank you all for opinions. ramsingh, thank you very much for you too.

ramsingh.. wats your problem? are you having a bad day? It happens to me sometimes. relax.