H-1B transfer and start date of employment

[mottai]

Hi folks,

I have found employment with a new company and they have filed for H-1B transfer. The new company lawyers have instructed the HR that I can start working based on the FedEx tracking information.

My understanding is that I can start working only based on the H-1B receipt notice from the USCIS. I searched the internet on H-1B portability stuff and found this link.

http://uscis.gov/graphics/publicaffairs/questsans/H1BChang.htm

The answer to Q.10 is

The portability provisions allow a nonimmigrant alien previously issued an H-1B visa or otherwise accorded H-1B status to begin working for a new H-1B employer as soon as the new employer files an H-1B petition for the alien.

Does this mean the lawyers are correct..? I would appreciate if someone would post a link or something from USCIS site to resolve this question. I can show the link to the HR and act accordingly.

Have fun...
Mottai