when you file 140, your received date is approximately PD

This PD will determine when you can file 485. Every month State of Departments issues a new visa bulletin, announcing cut-off dates information for all nationalities. If your PD falls before the cut-off date coordinating to your country of birth, you will be eligible to sub-mit 485. Take an extreme example, like the event on last July, all cut-off dates became current. Therefore, everyone rushed to sub-mit 485, no matter 140 approved or not.