Change of Employer after I-140 approval and before 180 days and Max out

[ap_reddy]

Experts,

I'm working with Employer-A and I'm  in my 6th year of H1B ,  maxout will be this Dec/2019.

My I-140 approved recently ( less than a month) , I got a new offer from Employer B.

Planning to join Employer B (full time , not a service based company) after approval only and expecting 3 years  extension will come.

If I join Employer B , and Employer- A withdraw I-140 petition, My validity for 3 years is still valid? ( As its not completed 180 days) 

I'll reject offer from Employer B, if answer is NO

Please help me