Ntn

I am in desperate need of answers for below Questions,

I am on j1 visa and i have got waiver of 2 yr requirement.Iam enrolling for
masters (F1) visa in Jan-04 session and my j1 visa/program is valid till
march-04.

My question:
1:I need to get released from my J1 sponsor on sevis to get i-20 issued to
me. If my J1 sponsor put my release date as dec-23rd and iam issued i-20
same day and I'll apply for change of status same day.would it be OK?

2: would i be out of status from dec23rd when iam released on sevis till
next 2-3 days before BCIS receive my request for change of Status.

3:I don;t have much knowledge about this but as i understood,J1 sponsor has
to realse me from sevis so that my school can issue
i-20,is this correct and do iam out of my j1 program the day iam realsed
from SEVIS or the day i apply my change of status.

4: how much time does BCIS Nebraska takes to change status.

Please advice and provide me with any other relevant information.