Will cross-chargeability apply to me?

I heard that there is something called cross-chargeability, and this could be applicable to me (let me know if I am wrong). My fiance is from Taiwan, and I am from China. We are planning to get married in about 6 months from now. My questions is, should we get married before I file I-140 (NIW)? At which point does this comes into play?

to Dora:

Yes if you get married and your spouse was born in Taiwan then cross-chargeability should apply to you. You can get married before or after filing NIW.

to Bella:

If you file I-485s using your spouse's country of birth (Taiwan) then yes, you can just do NIW.
I think it's probably better to get married before filing NIW.