Which Pay stubs are required during new H1b transfer

Right now i am working On L2 EAD and this employer filed for my H1b (New), it is still in “Initial reviews” .

Now this company is facing some financial issues and they can pay me till 30 sept only hence i will have paystubs till 30th sept only. I got another job and they are ready to transfer my H1b if it got approved.

But i have some questions:-

  1. When can i file for transfer?

2.Is it required to submit Pay Stubs with H1B visa for old company when H1B transfer is being done or we can still use the existing pay stubs with L2EAD status?

Please advise!!!