Here is my sister's renewal timeline - Her EAD was due to expire on March 02, 2017.

October 05, 2016 - Mailed Renewal Application
October 31, 2016 - Biometrics
December, 12, 2016 - I821 D Approved
December, 23, 2016 - EAD Received!

She received validity from March 03, 2017 till March 02, 2019 on her card