H1B transfer

Hello everyone,

I am currently on STEM opt. My h1b got picked in lottery but I have a fulltime offer from my client. The client is willing to do h1b transfer after I get h1b. I know everyone does h1b transfer but considering the current immigration scene, how long does it take for h1b transfer after we get h1b? Is there any rule that the employee should should stay with the employer who filed h1b for a certain time ? What is the complete process ? Are there risks involved ? If we get RFE how long does it take to process ? Is it advisable to travel during h1b transfer ?
#h1btransfer
Thanks in advance