Extension. Beyond 6 years

[Dkapoor0]

Hi, 

Can you please clarify few of my doubt with regards to new i140 rule.

Suppose I get my i140 approved with employer A and I stay with them for more then 6 Months. Now I understand that I can port my priority date when new employer will initiate my GC process.

Question is, Am I going to be eligible for extension after 6 years based on i140 approved with employerA? If employer B don't initiate right at the time of joining?

Can there be some gap when emoyer B initiate my GC process to get my priority date port or I must have to get it initiated right at the time of joining employer B to take advantage of porting old PD?