Just adding this one as added info. since I've been hearing reports that many have filed their AOS within 30 days as advised by their lawyers and they are now advising their friends to do the same. Filing for AOS successfully doesn't mean it is going to be approved automatically nor does having an EAD and working legally using it means the AOS will be approved when the time comes that one's AOS will be reviewed. Just be careful.
AOS Denials
The second thing to understand about AOS is that it is
discretionary, not mandatory. It is possible for a person who is technically eligible for immigrant status to nonetheless be denied adjustment of status in the exercise of discretion. The most common instances of such discretionary denials involve cases where the applicant abused the nonimmigrant process.
For example, if a person applies for admission into a school or for a change in nonimmigrant status
within 30 days of entry, they are presumed to have
acted in bad faith. That is, they had the preconceived intent to make the change and they used an easier to obtain visa in order to evade the normal screening process abroad for the visa they really wanted.
If the application occurs
between 30 and 60 days after entry, no presumption is made, but there is a
strong suspicion that the person may have acted in bad faith. The case will be scrutinized carefully. If the application occurs
more than 60 days after entry, the presumption is that the applicant acted in good faith. Both the USCIS and the State Department reserve the right to re-examine such cases, however, if there is any additional evidence of wrongdoing. If an AOS applicant has anything in his or her past visa history that suggests that he or she may have abused the visa process, or otherwise tried to take shortcuts, the USCIS has made it clear that they can and will deny such adjustment applications in the exercise of discretion. Discretionary AOS refusals are not subject to administrative review. While federal court review is theoretically possible, few judges are willing to attempt to substitute their judgment for that of USCIS officers in the absence of gross abuse of discretion.
Source