H1B transfer question

[Markbests]

I worked for company A on h1b, got lay-off and my last day was 2nd week of Feb. Now I have a job offer with company B & C, Company B has already filed my H1B transfer and have the receipt notice. Company C has filed my Labor and soon file my H1B transfer with in a week time. (As per the new 60 day H1B transfer rule , End of 1st week  April will be the 60 day grace period)

 

Question

 

1.    Can I join company B and work for them now, after months time give notice and join company c. Is it possible? 

2. Is it mandatory to provide company B receipt notice to company C for the transfer?; Since both are doing the transfer in parallel, also

company c is filling the application in premium.