I apologize if this info has been already known by anyone, but I found this very important for those applicants, who are going to file their DS-260 and I-485 forms after recent return to the the U.S.:
There is no more 30-60 days rule. If you want to file the petition to adjust status, you need to wait at least 90 days, otherwise it's assumed that you lied about the purpose of your travel at the port of entry.
(U) Inconsistent Conduct Within 90 Days of Entry:
(a) (U) However, if an alien violates or engages in conduct inconsistent with his or her nonimmigrant status within 90 days of entry, as described in subparagraph (2)(b) below, you may presume that the applicant's representations about engaging in only status-compliant activity were willful misrepresentations of his or her intention in seeking a visa or entry. To make a finding of inadmissibility for misrepresentation based on conduct inconsistent with status within 90 days of entry, you must request an AO from CA/VO/L/A. As with other grounds that do not require a formal AO, the AO may be informal. See .
(b) (U) For purposes of applying the 90-day rule, conduct that violates or is otherwise inconsistent with an alien’s nonimmigrant status includes, but is not limited to:
(iii) (U) A nonimmigrant in B or F status, or any other status prohibiting immigrant intent, marrying a United States citizen or lawful permanent resident and taking up residence in the United States; or
(iv) (U) Undertaking any other activity for which a change of status or an adjustment of status would be required, without the benefit of such a change or adjustment