H1B transfer again after 1 month while old one is pending status

[sstyahoo]

I was working for a employer X till Dec 28th of December 2018. I got laid off and started looking for job on my grace period, my visa and I-94 is valid till Jul-2020. my employer has initiated H1B withdrawal process.

Now I have two offer from employer A & employer B they both are asking me to join on receipt basis.

I am starting my H1B transfer process with both employer, since my grace period is going to end, I am planning to join employer A, as they will be little ahead in process and will get receipt with in a week so I can start the work from Feb 15.

However employer B is full time offer and I am more inclined to join them. but they are telling that their process is little slower and may take 4-5 weeks in getting receipt so I cannot wait for them as my grace period will be over by that time and I have to leave from US after Feb 28.

So please clarify my question below

1. I am planning to join employer A on Feb 15 and After I get receipt from employer B, Can I join employer B on receipt notice ?

2. will it be a case of bridge petition ?

3. if premium processing is resume by Feb 12, can I ask employer B is file my h1b transfer process in premium processing and if that approve, can I join employer B as that will be safe option 

4. what do you suggest in this case If I have any other option which I am not aware ?