I recently got a job offer in the US. My H1B visa gets activated by Sept 21st.

In October, I will be landing in the US about 15-18 days before joining, and in those 15-18 days, I plan to go on a different academic trip (presentation, as part of my previous college work, in no way connected with my employer) for a week outside the US.

I heard they give some certain "tracking" info on entering the US the first time.

Is there any extra paper work I need to fill to return to US after finishing my intermediate trip? Are there any complications to expect when I return from my presentation? Should I cancel my presentation trip, just to be safe?