Adjustment of Status - I-485

Hi Everyone, my wife and I are in the marriage-based I-485 adjustment of status process.

Also: My wife has been in the country during the entire I-485 process from our wedding day through today.

Here is our timeline:
March 27, 2015: Filed I-485 and other paperwork
April 27, 2015: Application received (our receipt date)
May 26, 2015: Biometrics appointment
July 4, 2015: Received online notice "Ready to schedule an interview"
July 5, 2015: EAD (work card) approved.
July 15, 2015: EAD card received.
...and then nothing else.

Essentially we have been in limbo waiting for the interview notice letter to arrive since July 4th. We have not received any RFE's. We have called USCIS many times but they can't tell us anything except what is on the USCIS website.

The USCIS website says as of August 31, 2015, the filing date of the last case completed before updating the chart has a receipt date of February 22, 2015. But this information does not reflect the receipt date of the cases they are working on today. Anyway, I'm not sure about the reliability of the information on the USCIS website.

Does anyone know the receipt date of the cases that the Houston field office is working on today?

For people with application receipt dates on or after April 27th only:
Has anyone in the same situation (marriage-based I-485 adjustment of status; wife always in the U.S.) received their notice for their interview date yet?

For everyone else, can you please share your Houston field office timeline and experiences?

Ultimately, we are trying to estimate dates when we will get our interview notice and green card.

Thank you all in advance for your help and answers to my questions. :-D