H1B amendment query for client change before fly

Hi ,

My H1B stamping was done a week back on passport. Due to some circumstances i need to go to different client instead of my current client (My petitioner will remain same), I have few queries and it will be a great help if red bus help me on it:

For client change in same location (18 miles) do I need to file an amendment

Can I fly to US and then initiate amendment from US (any legal complexity) or it is mandatory to initiate before fly

If I initiate amendment after fly to US then is there any issue during POE or when I file amendment after arriving US

Can I fly to US while my amendment in progress

What is turnaround time for amendment completion (average)

Mandeep

Better enter into US first and then file amendment(even amendment may not be required as the new work location is just 18 miles from your approved LCA location).

It will take some days to file amendment after i enter US. During these days can i work for my new client or it can be consider as violation of USCIS laws?

My case is the same as mentioned in this question. I just wanted to know if there is any minimum wait time for filing the amendment? Or can the amendment be filed immediately after I join the US office of my petitioner?