H4 to H1B with I-140 approved in the past

[ThankYouForHelp]

I was with Company A on H-1B for 6 years until 2015 but had to take a work break in 2015 so transferred to H4 visa. I have been working for Company B on H4-EAD for 3 years. I started with Company B as a contractor and converted to full-time for 5 months now.
 
I have my I-140 Approved with Company A for EB2 with a Priority Date of Sept 2012. The Filing Date is current for me now and most probably the Final Action Date will also be current in a few months, as it is already May 2012 now.
 
I spoke with Company A and they are ready to rehire me on H-1B so that they can file for my GC. However, I still have to talk to my current employer Company B to see if they agree to change my full-time position to contracting. I have some questions in that situation:
 
(1) If I change my visa to H1-B with my former Company A, will they be able to file for my GC as soon as my H1-B is approved or will they have to wait for some time before they can file my GC?
 
(2) My current employer Company B will ask me for how long do I have to be with them as a Contractor. So, I want to know approximately how long will the whole process take to transfer from H4 to H1-B and then apply for GC and get GC in hand.
 
Thank you for reading this long post. Will appreciate your inputs!

[Zodiac System]

You could get started with Company A immediately on H4-EAD, while your COS from H4 to H1 is being processed.  Change of Status from H4 to H1b could be done within 3 weeks, in premium processing which includes time for LCA certification.  Consult company A's attorney regarding your GC processing and timeline.  If your dates are current, he should be able to start your GC processing too simultaneously.  Good Luck.

Edited December 3, 2021 by Zodiac System

[ThankYouForHelp]

On 12/3/2021 at 8:57 AM, Zodiac System said:

You could get started with Company A immediately on H4-EAD, while your COS from H4 to H1 is being processed.  Change of Status from H4 to H1b could be done within 3 weeks, in premium processing which includes time for LCA certification.  Consult company A's attorney regarding your GC processing and timeline.  If your dates are current, he should be able to start your GC processing too simultaneously.  Good Luck.

Thank you so much for your detailed response. I appreciate it. I will talk to Company A and get the process started soon. Wish you a Merry Christmas and a prosperous New Year. Appreciate your response so much. God Bless!!!