I'll have Orientation before few days my work begins. I don't know if that is going to be a paid one. I am guessing yes, because it is a whole day (8hrs). Will that be considered work? What might be the consequences of working before the date printed on the OPT card?
Anybody gone through this situation? Suggestions please!
Thank you

I was in a kind of same situation. My OPT would start after an week my CPT would end. I took vacation and didn;t work for the days when I had no work authorization. If I were you I would avoid working until I get my OPT.

It won't be any problem while working before OPT card arrives, afterall you can volunteer. You will be paid from the date you submit OPT card.

I already have the card but the organization is scheduling me to work 2 day before the date on opt card. What might be the consequences?

Do you start work on the same month as the start date on your opt card? If so, I don't see a problem with starting work merely 2 days before your card gets there. You will be paid for that month anyways, and more often than not, your paycheck won't specify what dates in the month you worked; it will just say you worked the month of June, for example. 

Even if it isn't the same month, I don't think it is a big deal. Is it legal? Technically, no. Will there be consequences if you start a couple days early? I highly doubt it. Fret not, start your work. I wish you good luck in your new job.