CPT authorisation waiting , grace period

Hi ,sevis is transferred to new college on Dec 15th 2019,I was on stem OPT ,now I am waiting for CPT authorisation confirmation from new college, in case if the authorization is not confirmed what is the grace period I will have to leave USA

Well, I am not sure, if there is any grace period as such…It should be automatic in my view, unless the SEVIS records were deleted. You need to ask your DSO on the SEVIS records transfer and then act accordingly, If any issues, you may need to file re-instatement of F1. Talk to your DSO.