回複：thank you

My lawyer told me that it takes 2 years to get I-485 approved, and I-864 needs to show the last 3 years tax return, so after 1 year or 2, INS will send you a package to ask you to prepare for I-864 again with the newest tax return and employment info of the sponsor, sp it is not neccessary to do it now.

But if you want to be ultra-sure, you can prepare this document.