It starts with the date when the corresponding status was acquired. In case you wonder where you may find the date – it can be found on your green card. Look for where it says “Resident Since:” right at the bottom.
You should not be misled by the fact that the Resident Since data does not coincide with the very same date when the card was delivered. For instance, in case you have an embassy of America in the country you are staying in, you will get the card there – then the green card is delivered to your USA address so that the dates coincide.
However, in case you do not possess the card, you can figure out your permanent resident date using some other documents.
A Form I-797 Notice of Action or consular letter – those are the types of documents that can give you a clue about the start of your residentship date. The truth is that the date on such a letter can be considered the precise date you need.
March 14, 2019