There will not be any update on GCKEY at all. ECAS certainly change once your app forwarded to respective spouse's VO.
You will notice total 4 lines and line number 2 will say when they started to process spouse application. Example is below for my spouse app:
- We received (spouse name)'s application for permanent residence on April 4, 2018.
- We started processing (spouse name)'s application on June 26, 2018.
- We sent (spouse name) medical instructions on May 18, 2018. To avoid delays, please provide us with the information requested as soon as possible. Please consider delays in mail delivery before contacting us.
- Medical results have been received.
Hope it helps.