H1B visa - Start Date

[jojupi01]

Currently I am transfering my H1B visa from company A to company B. The company B have mailed my paperwork last thursdayand they have asked me to start, coming monday.

I would like to know

1)It is safe to start with just the FedEx acknowledgement receipt?

2) Or do i have to wait for my formal CIS receipt notice, if so how long will it take to process the receipt notice.

Thanks.

 

[manwithnoname]

You can start with the FedEx receipt as when you receive the receipt notice, it will contain 2 dates: Receipt date RD, (date on which the service center received the application) and Notice date ND, (date on which the notice is generated). You will receive the notice a few days, after the ND. But USCIS will honor the RD which usually coincides with the courier's receipt.