Hello,
Could you please advise what is the safe way to proceed for me?

My situation: I am on H1B visa with employer A (expires in Sept.20, I got a job offer from employer B, the H1B transfer will be filed this week. I was told by the lawyer that it will take 7 bus. days until the answer arrives (premium).
What I need to know: can I start working for employer B prior to the H1B transfer approval arrives?

Also, I am getting married with my fiance (US citizen), so we are worried wether it is risky to quit my old job (how long will it take to get work authorization after we marry?) before H1B transfer approved or it's O.k.?

We want to be sure that I will not be without a right to work even if H1B transfer fails.

What would you advise? Thank you