H1B Transfer denied and previous employer visa valid till July 2020

[lokeshk99]

Employer A visa valid till July 2020 and not yet revoked.

Joined Employer B in March and transfer got denied on July 4th.

Got job with Employer C and started filing.

Question:

Within how many days Employer C need to submit the transfer docs ?

Can I join Employer C on receipt OR should leave to India ?

Please suggest