Visa Transfer

I am currently in the process of H1 visa Transfer. I got an offer from a company and I accepted it and initiated a visa Transfer because of layoffs and other issues in my company. But then I got a much better offer from a different company and they're yet to start my visa transfer. I received my H1 transfer receipt from the first company now. What should I do? Should I require to join the first company before joining the second or can I work in my current company until the second company's transfer gets approved.? Please advise...