Apply for H1B before or during B1 visit to USA

[tsarina]

I have a previously-planned business trip to USA using my B1/B2 visa, my business trip date is very soon.

I may also get soon an offer from a US employer and the employer needs to file an H1B petition with remainder option.

Are the following options possible and is one of them better?

1) File H1B ASAP before my B1/B2 visit to USA:

In this case, when I enter USA for my business trip on B1 visa, my H1B petition will be still under processing. Is that OK? Can I enter USA? Would that affect my H1B application?

2) File H1B after my entry to US, during my stay there on B1/B2 visa:

I would enter USA on my B1 visa and while I am there, my employer would start my H1B petition. Is this option possible? Does it have impact on my H1B application?

My business trip is for 3 months. After H1B is approved, I will get back to my country to stamp the visa on my passport and get back to work there. In both cases, if my H1B is not approved yet, can I leave USA at any time or am I bound to wait in US for approval?

[tsarina]

Note that in my B1/B2 business trip, I will not be working. The US employer who gave me the offer is a company. I will just be at a university pursuing research without getting paid.

[pontevecchio]

Both are possible and legal .