Dear Teacher 8:
I am very suprised when my PR case tracker sent me alerts. I see "Case Was Approved" and "New Card Is Being Produced" status in last two days, but my Priority Date is still not current yet (there is still 3 months away from the final action date in the visa bulletin).
My question is what should I do once I have received the card:
1. Keep the card without doing anything.
-No!
what is the impact/risk down to the road?
-It will result in big trouble to you when you renew your green card or apply for the naturalization in the future.
2. Return it to somewhere of USCIS? Call them or go to local field office?
-Call USCIS to check the I-485 status. If it has been approved as you mentioned, then ask them to re-open your I-485; if they cannot do it for you, then you need to file I-290B Motion to reopen your I-485.
Another problem is that if you work with H-1B status, then you also need to ask your employer to file I-290B Motion to reopen to reinstate your H-1B status (talk to your employer or lawyer). If you work using EAD or you do not work at all, then your employer or you do not need to anything for your status.
Please contact USCIS as soon as possible; the sooner the more probability USCIS to reopen your I-485. Thus, you do not need to file I-290B.