Back to 2001, I checked the law

It said: "You may start to work after you file the petition". And my lawyer insisted that I wait until we got the receipt notice. It took me 70 days that moment. My lawyer told me, it is only 100% legal to work, after I got the receipt. But I know most people just start to work for the new company after they FedEx to CIS and get the FedEx receipt.

Because CIS may reject this petition due to all kinds of reasons (lack of documents etc). And when you receive the receipt, it means no rejection.