Can I work for my company before getting the physical EAD card of OPT

I have received approval for my OPT, and I received a note stating that my start date is June 5th. However, I haven’t received my physical OPT EAD card yet. Can I begin working from June 5th even without having the physical EAD card?

Disclaimer: I’m not an immigration attorney.

I guess no. You need physical EAD card before you can start working. I’m deriving this from H4 EAD question I had.