Query on H1B Transfer and joining new Employer

[RPS]

Hi Team,

My current scenario like below - 

I'm employed with A and working for client B. My current visa validity is till 31st March,2018 and I-94 validity is till 10 April,2018.

My current employer has not filed extension for me. My future employer will be  B (my current client). But due to less number of remaining days for my visa validity, I have some query.

1. If my future employer is able to file the H1B transfer by 31st March but receipt for H1B transfer not received by 31st March, what will be my available options.  (Consider I will be resigning from my current employer A and my last working date is 31st March,2018).

2. If my future employer is able to file only after 31st March but  get receipt before 10th April, will I be able to join my new employer B  on receipt notice? (Consider I will be resigning from my current employer A and my last working date is 31st March,2018).