We can file a WOM only 6 months after fingerprint. Is this true?

My I485 has been pending by NC since Mar, 2004. I'm planning to file a WOM.

I had a fingerprint for I485 this month (Apr, 2007). My last fingerprint was Jan, 2006. My attorney said it's 15 month regular fingerprint.

My attorney also said, I can file a WOM 6 months later, otherwise, judge may say I didn't give INS enough time to process my I485.

Is this true? Do I have to wait another 6 month to file WOM?

Thanks very much.