Need help for an urgent H1B transfer case!!!!

I worked for University A for one year with H1B visa

Recently started working in University B. I received the H1B transfer receipt, but the case is still pending.

However, my H1B visa at A is still active and they told me that I can go back and work for A if I want.

I do have an option to work in University C.

My question is whether I can transfer my H1B visa to university C from A when H1B visa transfer to B from A is pending? or I have to wait until I receive approval notice for H1B transfer from A to B?

Disperate to get your inputs! Thank you a lot amd Happy New Year!!!