I-485 question

My father applied I-130 for me, and I received I-130 approval notice.

Now I am filling in the form of I-485, it also requires I-864(Affidavit of Support) abd I-693(medical examination). Someone told me that it is not neccessary to file I-693 or I-864 now, since I-485 will take 2 years, but I-693 will be only valid for 6 months, while I-864 is only used during the final step of waiting for I-485 approval.

Is that true?

Thanks a lot.