AOS / GC - Need to understand the timeline and Job change possibility

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Hi,
I want some help to understand the timeline to receive GC and the possibility of switching employer while GC is in process.

I am currently on L1-A Visa.

My current employer applied for AOS and EAD (concurrent filing).
- Application received ---------------------------- April 11 2016
- Finger print notice received dated -------------- May 06 2016
- Finger Printing completed on ------------------- May 24 2016
- EAD + Advance Parole card received on ------- May 26 2016

Now the application is being processed at Nebraska.

Any idea how long after receiving the EAD+Advance Parole card can I expect to receive my GC?

The category I am applying for is:
- Multinational Executive or Manager
- EB1

Second part of my question is, is it advisable to switch job? Either within the same company or new employer?
What are the consequences of doing so.

Thanks for any help.