__________________Self filed AOS │Apps Received By USCIS - 3/18/19 │Biometrics Done - 4/11/19
Interview Scheduled - 4/24/19│Interview Date - 5/31/19│AOS Approval - 5/31/19
Permanent Resident Card Received - 6/8/19
The reason why some are told 2 weeks vs 4 weeks is simple.
If your receipt says your SSN should arrive within 2 weeks, your information was verified by DHS on the spot when you applied for the SSN. All that's left is to issue you an SSN and create the SSN card and mail it to you.
If your receipt says you need to wait 4 weeks, your information wasn't verified by DHS and it will take longer to manually verify your information.