Is it ok to travel on B1 for the same client for which one already has a stamped H1B Visa though not effective yet? If yes, what should be the ideal duration? And what problems can one expect to face at port of entry.
There is no problem. Just let CBP at port of entry know which visa you are entering on. Make sure you have some document that shows purpose of visit and proof that you have a place to stay. These may or may not be requested at entry.
Best wishes
Dr. Sandeep Shankar